Weight loss during treatment is associated with reduced disease-free survival in non-metastatic breast cancer
Original Article

Weight loss during treatment is associated with reduced disease-free survival in non-metastatic breast cancer

Juliana Goulart Xande1 ORCID logo, Luiz Vinicius de Alcantara Sousa1 ORCID logo, Nathalia Aguiar Silva Jesus1, Marcela Ferraz Brenna1, Jean Henri Maselli-Schoueri2 ORCID logo, Auro del Giglio1 ORCID logo

1Department of Oncology, Centro Universitário Faculdade de Medicina do ABC (FMABC), Santo André, SP, Brazil; 2Princess Margaret Cancer Centre, Division of Medical Oncology and Hematology, Department of Medicine, Melanoma and Skin Cancer, University of Toronto, Toronto, Ontario, Canada

Contributions: (I) Conception and design: A del Giglio; (II) Administrative support: All authors; (III) Provision of study materials or patients: All authors; (IV) Collection and assembly of data: JG Xande, MF Brenna, NAS Jesus; (V) Data analysis and interpretation: All authors; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.

Correspondence to: Auro del Giglio, MD, PhD, FACP. Department of Oncology, Centro Universitário Faculdade de Medicina do ABC (FMABC), Avenida Príncipe de Gales, 821, Santo André, SP 09060-650, Brazil. Email: aurodelgiglio@gmail.com.

Background: Breast cancer prognosis is influenced by host-related factors beyond tumor stage and molecular subtype, including body composition dynamics and systemic inflammation during treatment. The prognostic impact of weight variation throughout oncological therapy, particularly within the Brazilian public health setting, remains poorly characterized. The primary objective was to determine whether percentage weight variation during treatment is associated with disease-free survival (DFS) in non-metastatic breast cancer

Methods: This retrospective cohort study included 184 female patients treated for breast cancer at Hospital Anchieta in Brazil between January 2020 and December 2024. Clinical data, anthropometric measurements (percentage weight variation from baseline to last follow-up), and pretreatment hematological inflammatory indices—specifically neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and absolute lymphocyte count (ALC)—were collected. Due to limited data availability, analyses involving inflammatory markers were considered exploratory. Multivariate Cox proportional hazards models were used to assess associations with DFS and overall survival (OS), stratified by clinical stage.

Results: The cohort had a mean age of 56.3±12.2 years; 83.7% had excess body weight (38.2% overweight, 45.5% obese). Luminal B was the most prevalent molecular subtype (46.4%); and 91.8% had non-metastatic disease (stages I–III). In patients with stages I–III, percentage weight variation was associated with DFS in multivariable analysis (hazard ratio 0.95; 95% confidence interval: 0.92–0.98; P=0.002), with weight loss linked to higher recurrence risk compared to those with stable weight or weight gain. No statistically significant associations were observed for OS. While weak univariate correlations existed between specific inflammatory markers and weight balance, NLR and PLR were not associated with DFS in the analyses performed.

Conclusions: Maintaining body weight during systemic therapy is associated with improved DFS in patients with non-metastatic breast cancer in this cohort. Routine monitoring of anthropometric dynamics should be an integral component of supportive oncological care.

Keywords: Breast neoplasms; body weight changes; neutrophil-to-lymphocyte ratio (NLR); prognosis; disease-free survival (DFS)


Received: 01 February 2026; Accepted: 18 May 2026; Published online: 29 June 2026.

doi: 10.21037/abs-2026-1-0005


Highlight box

Key findings

• In women with non-metastatic breast cancer treated in a public health setting, percentage weight variation during systemic therapy was associated with disease-free survival (DFS).

• Patients who experienced weight loss during treatment had a significantly higher risk of disease recurrence compared with those who maintained or gained weight.

• Systemic inflammatory markers derived from routine blood counts, including neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR), were not significantly associated with DFS in the analyses performed in this cohort.

What is known and what is new?

• In a real-world cohort from a Brazilian public hospital, this study demonstrates that weight loss during treatment is associated with worse DFS in patients with non-metastatic breast cancer.

• These findings highlight the potential prognostic relevance of anthropometric changes during therapy in this setting.

What is the implication, and what should change now?

• Weight variation during systemic therapy should be routinely monitored as part of comprehensive oncological care.

• Early identification of patients experiencing unintentional weight loss may support timely nutritional and supportive interventions.

• Further prospective studies are needed to clarify the mechanisms linking metabolic changes, systemic inflammation, and cancer progression, and to evaluate whether targeted strategies to prevent detrimental weight loss during treatment can improve clinical outcomes.


Introduction

Breast cancer remains the most frequently diagnosed malignancy among women worldwide (1) and is the leading cause of cancer death in the female population in Brazil (2). While significant advancements in early detection and multimodal treatments—including surgery, chemotherapy, radiotherapy, hormone therapy, and targeted agents—have substantially improved survival rates (3,4), patient prognosis is still heavily influenced by host-related factors that extend beyond standard tumor clinicopathological characteristics like stage and molecular subtype (5,6). Among these emerging prognostic factors, body composition dynamics and systemic inflammatory status during treatment have garnered increasing attention (7-10).

Obesity at diagnosis is a well-established risk factor for the development of postmenopausal breast cancer and is associated with poorer overall survival (OS) (11,12). However, the impact of weight variation during oncological treatment is more complex and paradoxical. While significant weight gain is a common and distressing side effect of adjuvant chemotherapy and endocrine therapy (13,14), potentially compounding cardiovascular risks and recurrence (15), unintentional weight loss is often an ominous sign (16). In the context of cancer, involuntary weight loss frequently indicates cancer-associated cachexia—a multifactorial syndrome characterized by systemic inflammation, metabolic dysregulation, and the progressive loss of skeletal muscle mass (sarcopenia), which is strongly linked to increased treatment toxicity, reduced quality of life, and decreased survival (16). The relationship between weight loss and age is also clinically relevant: older patients, particularly those who are postmenopausal, tend to have reduced physiological and nutritional reserve, making them more vulnerable to treatment-related weight loss, sarcopenia, and functional decline during oncological therapy (15,16).

Intricately linked to metabolic changes is the host’s systemic inflammatory response. The tumor microenvironment actively promotes systemic inflammation, which in turn can facilitate tumor progression, metastasis, and treatment resistance (5,17). Routine hematological markers available from standard complete blood counts (CBC), such as the absolute neutrophil count, lymphocyte count, and platelet count, reflect this inflammatory state (17). Composite ratios derived from these parameters—specifically the neutrophil-to-lymphocyte ratio (NLR) and the platelet-to-lymphocyte ratio (PLR)—have emerged as cost-effective, easily accessible biomarkers (18,19). Elevated NLR and PLR, reflecting a protumoral inflammatory milieu and an impaired antitumor immune response, have been associated with poor prognosis across various solid tumors, including breast cancer (20,21).

Despite the individual recognition of weight variation and inflammatory markers as prognostic indicators, their interrelationship and combined impact on clinical outcomes in a real-world clinical setting remain under-explored, particularly within the Brazilian public health context. We hypothesize that weight variation during treatment is independently associated with disease-free survival (DFS) in non-metastatic breast cancer, and that baseline systemic inflammatory markers correlate with weight change. Given the retrospective design, we acknowledge that causal mechanisms cannot be established. Therefore, this study aimed to evaluate the association between weight variation during treatment and inflammatory markers [NLR, PLR, C-reactive protein (CRP)] in women with breast cancer treated at a public hospital, and to determine the prognostic value of these factors for DFS and OS. The primary objective was to assess the association between percentage weight variation and DFS; secondary exploratory analyses included inflammatory markers (NLR, PLR, and CRP). We present this article in accordance with the STROBE reporting checklist (available at https://abs.amegroups.com/article/view/10.21037/abs-2026-1-0005/rc).


Methods

Study design and patient selection

This was an observational, analytical, retrospective cohort study conducted at Hospital Anchieta in São Bernardo do Campo, São Paulo, Brazil. Data collection was carried out between June 2025 and August 2025 through a review of electronic medical records. Patients included in this study were diagnosed with breast cancer between January 2020 and December 2024.

The study population consisted of adult female patients (aged 18 years or older) diagnosed with non-metastatic breast cancer [stages I–III, International Classification of Diseases, 10th Revision (ICD-10) code C50]. To be eligible for inclusion, patients must have received systemic oncological treatment—defined as chemotherapy, hormone therapy, immunotherapy, or targeted therapy—at the hospital’s oncology outpatient clinic. Furthermore, inclusion required the availability of essential data in the medical records, specifically anthropometric measurements (weight and height) and relevant laboratory test results over the course of treatment.

Patients were excluded if they were male, under 18 years of age at diagnosis, or if their medical records were incomplete, lacking the essential data points necessary to address the study’s primary objectives. Patients with confirmed metastatic disease (stage IV) at diagnosis were included for descriptive purposes but excluded from all survival analyses. The patient selection process is summarized in Figure S1.

Data collection and variables

Following the application of eligibility criteria, clinical, pathological, and anthropometric data were extracted from patient charts. The variables analyzed included age at diagnosis, menopausal status, comorbidities (such as hypertension, diabetes, dyslipidemia, and hypothyroidism), lifestyle factors (smoking and alcohol consumption), histological subtype, molecular subtype (luminal A: ER+ and/or PR+, HER2−, Ki-67 <20%; luminal B: ER+ and/or PR+, HER2−, Ki-67 ≥20%, or HER2+; HER2-enriched: ER−, PR−, HER2+; triple negative: ER−, PR−, HER2−; luminal hybrid: ER+ and/or PR+, HER2+), TNM staging at diagnosis, and treatment modalities (neoadjuvant, adjuvant, and palliative chemotherapy, hormone therapy, radiotherapy, and surgery).

Anthropometric assessment included weight (kg) and height (m). Body mass index (BMI) was calculated as weight divided by height squared (kg/m2) and categorized according to World Health Organization standards: underweight (<18.5 kg/m2), normal weight (18.5–24.9 kg/m2), overweight (25.0–29.9 kg/m2), and obesity (≥30.0 kg/m2). Weight variation was calculated as the percentage difference and absolute difference (kg) between the baseline weight recorded at the beginning of treatment and the last available weight measurement during the follow-up period. Percentage weight variation was defined as: [(last weight − baseline weight)/baseline weight] ×100%, where negative values indicate weight loss and positive values indicate weight gain. For categorical analyses, patients were classified into: weight loss (≥5% decrease), stable weight (within ±5%), and weight gain (≥5% increase). Weight was measured using calibrated clinical scales at each oncology consultation, with frequency varying by treatment modality (typically every 2–4 weeks during chemotherapy and at each follow-up visit thereafter). Weight variation was computed using the first recorded weight (at treatment initiation) and the last available weight during follow-up.

For a refined analysis, percentage weight variation during chemotherapy was additionally calculated for patients receiving systemic treatment. In this analysis, weight change was defined as the percentage difference between baseline weight (measured prior to chemotherapy initiation) and the closest available weight measurement at the end of chemotherapy. This analysis was performed separately for patients receiving neoadjuvant and adjuvant chemotherapy. Patients who did not receive chemotherapy were not included in this analysis, as baseline weight measurements prior to surgery were not consistently available, precluding reliable estimation of perioperative weight variation.

Laboratory data included hematological parameters (erythrocytes, hemoglobin, leukocytes, neutrophils, lymphocytes, platelets) and metabolic markers [fasting glucose, glycated hemoglobin (HbA1c), total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides]. Inflammatory markers were assessed using CRP and derived cellular ratios: the NLR, the PLR, and the absolute lymphocyte count (ALC).

Assessment of systemic inflammatory markers

Systemic inflammatory status was evaluated using hematological parameters derived from routine baseline CBC obtained prior to the initiation of systemic treatment. The NLR was defined as the absolute neutrophil count divided by the ALC. The PLR was calculated by dividing the absolute platelet count by the ALC. Serum CRP levels (mg/L) were recorded as a biochemical marker of inflammation.

Statistical analysis

Data analysis was performed using Stata software. Categorical variables were described as frequencies and percentages, while continuous variables were presented as mean ± standard deviation (SD) or median and interquartile range (IQR). Comparisons between groups were performed using the Chi-squared test or Fisher’s exact test for categorical variables, and the Mann-Whitney U test or t-test for continuous variables. Correlations were assessed using Pearson’s (r) or Spearman’s rank correlation coefficient. Survival analysis was conducted using the Kaplan-Meier method. Prognostic factors for DFS and OS were evaluated using univariate and multivariate Cox proportional hazards regression models, reporting hazard ratio (HR) and 95% confidence interval (CI). Statistical significance was set at P<0.05 for all analyses.

For multivariable Cox regression, the number of variables included in the model was limited in relation to the number of observed events to reduce the risk of overfitting. The final model included four variables selected based on clinical relevance and data availability: percentage weight variation, molecular subtype, tumor-node-metastasis (TNM) stage group (I–II vs. III), and Ki-67 (continuous).

Ethical consideration

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Research Ethics Committee of Centro Universitário FMABC (CAAE: 86344925.0.0000.0082) and informed consent was waived due to the retrospective nature of the study.


Results

Patient characteristics

A total of 184 female patients were included in the analysis, with a mean age at diagnosis of 56.3±12.2 years. Stage IV patients were included for descriptive purposes but excluded from all survival analyses. At baseline, most patients presented with excess body weight, with 38.2% classified as overweight and 45.5% as obese, resulting in a mean BMI of 30.0±6.3 kg/m2. Luminal B was the most prevalent molecular subtype (46.4%), followed by triple negative disease (22.4%). Most patients were diagnosed with stages IIA (24.5%) and IIB (19.0%), while 8.2% presented with metastatic disease at diagnosis. Baseline characteristics are summarized in Table 1 and stratified by molecular subtype in Table S1.

Table 1

Baseline demographic, clinical, pathological, treatment, and anthropometric characteristics of the study population

Characteristic Value
Age at diagnosis (years) (n=184) 56.3±12.2
BMI (kg/m2) (n=178) 30.0±6.3
   Underweight (<18.5) 1 (0.6)
   Normal weight (18.5–24.9) 28 (15.7)
   Overweight (25.0–29.9) 68 (38.2)
   Obesity (≥30.0) 81 (45.5)
Menopausal status
   Pre-menopause 54 (29.3)
   Post-menopause 117 (63.6)
   Perimenopause 13 (7.1)
Molecular subtype
   Luminal A 33 (18.0)
   Luminal B 85 (46.4)
   HER2-enriched 10 (5.5)
   Triple negative 41 (22.4)
   Luminal hybrid 12 (6.6)
TNM stage
   Stage IA 20 (10.9)
   Stage IIA 45 (24.5)
   Stage IIB 35 (19.0)
   Stage IIIA 32 (17.4)
   Stage IIIB 25 (13.6)
   Stage IIIC 8 (4.3)
   Stage IV 15 (8.2)
Chemotherapy (n=184)
   Neoadjuvant chemotherapy 93 (50.5)
   Adjuvant chemotherapy 60 (32.6)
   Palliative chemotherapy 39 (21.2)
Pathological features
   Histological type
    Invasive ductal carcinoma 159 (86.4)
    Invasive lobular carcinoma 5 (2.7)
    Other 19 (10.3)
   Nottingham grade
    Grade I 17 (9.2)
    Grade II 96 (52.2)
    Grade III 31 (16.8)
   Ki-67 index
    Continuous (%) 20.0 (5.0–90.0)
    <20% 101 (54.9)
    ≥20% 81 (44.0)
TNM components
   T category
   T1 3 (1.6)
   T2 43 (23.4)
   T3/T4 53 (28.8)
   N category
   N0 35 (19.0)
   N1–N3 63 (34.2)
Treatment history
   Surgery type
    Breast-conserving surgery 88 (47.8)
    Mastectomy 69 (37.5)
   Chemotherapy regimen
    Anthracycline + taxane 124 (67.4)
    Other/none 29 (15.7)
   Radiotherapy 137 (74.4)
   Endocrine therapy 116 (63.0)
Comorbidities & lifestyle
   Hypertension 73 (39.7)
   Diabetes mellitus 25 (13.6)
   Dyslipidemia 21 (11.4)
   Smoking
    Never 124 (67.4)
    Former/current 58 (31.5)
   Alcohol consumption 20 (10.8)
   Weight dynamics (%) −3.7 (−41.1 to +24.8)

Data are presented as mean ± standard deviation, n (%), or median (range). , palliative chemotherapy refers to systemic chemotherapy administered with non-curative intent in patients with stage IV (metastatic) disease or with disease recurrence. BMI, body mass index; HER2, human epidermal growth factor receptor 2; TNM, tumor-node-metastasis.

Factors associated with disease progression and survival

Disease recurrence occurred in 27.7% of patients, and 20.2% died during the follow-up period. In univariate analyses, higher Ki-67 expression (P=0.004) and advanced TNM stage (P<0.001) were significantly associated with disease recurrence. Additionally, advanced TNM stage was significantly associated with recurrence in categorical analysis (P<0.001), whereas menopausal status and histological type were not (Table 2). For DFS, Kaplan-Meier analysis identified molecular subtype (P<0.001) and BMI category (P=0.02) as significant prognostic factors (Table 3; Figure S2). However, when BMI was analyzed as a continuous variable in Cox regression models, it was not significantly associated with DFS (HR 1.03; P=0.21); the correlation between baseline BMI and percentage weight variation is illustrated in Figure S3. Inflammatory markers, including NLR, PLR, and CRP, were not significant predictors of DFS. Regarding OS, molecular subtype remained significant (P=0.007), and Ki-67 (HR 1.02; P=0.003), NLR (P=0.03), and PLR (P=0.006) were associated with OS in univariate Cox analysis (Table 3; Figure S4; Table S2).

Table 2

Association of menopausal status, TNM stage, and histological type with disease recurrence in non-metastatic patients (n=169)

Variable Total, n No recurrence, n (%) Recurrence (DFS event), n (%) P value
Menopausal status 0.31
   Premenopausal 49 34 (69.4) 15 (30.6)
   Postmenopausal 107 86 (80.4) 21 (19.6)
   Perimenopausal 13 10 (76.9) 3 (23.1)
TNM stage <0.001
   Stage 0 (in situ) 4 3 (75.0) 1 (25.0)
   Stage I 20 18 (90.0) 2 (10.0)
   Stage IIA 45 39 (86.7) 6 (13.3)
   Stage IIB 35 30 (85.7) 5 (14.3)
   Stage IIIA 32 24 (75.0) 8 (25.0)
   Stage IIIB 25 10 (40.0) 15 (60.0)
   Stage IIIC 8 6 (75.0) 2 (25.0)
Histological type 0.63
   Invasive ductal carcinoma 135 102 (75.6) 33 (24.4)
   Invasive lobular carcinoma 8 7 (87.5) 1 (12.5)
   Mucinous 1 1 (100.0) 0
   Micropapillary 3 3 (100.0) 0
   Papillary 4 3 (75.0) 1 (25.0)
   Mixed/other 16 14 (87.5) 2 (12.5)

DFS, disease-free survival; TNM, tumor-node-metastasis.

Table 3

Univariate survival analysis for DFS and OS

Variable DFS OS
HR (95% CI) P value HR (95% CI) P value
BMI (kg/m2) 1.03 (0.98–1.08) 0.19 1.02 (0.97–1.08) 0.18
Ki-67 (%) 1.02 (1.00–1.03) 0.055 1.02 (1.01–1.03) 0.003
NLR 1.05 (0.95–1.16) 0.35 1.10 (1.01–1.20) 0.030
PLR 1.00 (0.99–1.01) 0.61 1.01 (1.00–1.01) 0.006
CRP (mg/L) 1.01 (0.99–1.03) 0.36 1.01 (0.99–1.03) 0.21
Weight variation (%) 0.97 (0.95–0.99) 0.01 0.97 (0.94–0.99) 0.008
BMI category (log-rank) 0.02 0.24
Molecular subtype (log-rank) 0.001 0.007

BMI, body mass index; CI, confidence interval; CRP, C-reactive protein; DFS, disease-free survival; HR, hazard ratio; NLR, neutrophil-to-lymphocyte ratio; OS, overall survival; PLR, platelet-to-lymphocyte ratio.

A focused multivariate Cox regression model including four pre-specified variables (weight variation, molecular subtype, TNM stage group, and Ki-67), selected in accordance with events-per-variable conventions, identified percentage weight variation as a significant predictor of DFS among non-metastatic patients (stages I–III) (HR 0.95; 95% CI: 0.92–0.98; P=0.002), indicating an approximate 5% reduction in the risk of disease recurrence for each percentage point of weight maintenance or gain (Table 4). No variables were independently associated with OS in the adjusted model.

Table 4

Multivariate Cox regression analysis for DFS and OS in non-metastatic patients (stages I–III)

Outcome Variable HR 95% CI P value
DFS
   Stage I–III Weight variation (%) 0.95 0.92-0.98 0.01
   Stage I–III Molecular subtype (TN vs. Lum A) 1.176 0.357–3.870 0.79
   Stage I–III Molecular subtype (HER2 vs. Lum A) 0.977 0.180–5.300 0.97
   Stage I–III Molecular subtype (Lum B vs. Lum A) 0.431 0.140–1.322 0.14
   Stage I–III TNM stage III vs. I/II 2.744 1.331–5.656 0.006
   Stage I–III Ki-67 (%, continuous) 1.005 0.986–1.025 0.58
OS
   Stage I–III Weight variation (%) 0.99 0.96-1.02 0.73
   Stage I–III Molecular subtype (TN vs. Lum A) 1.283 0.283–5.819 0.74
   Stage I–III Molecular subtype (HER2 vs. Lum A) 1.672 0.254–11.023 0.59
   Stage I–III Molecular subtype (Lum B vs. Lum A) 0.589 0.143–2.421 0.46
   Stage I–III TNM stage III vs. I/II 1.473 0.662–3.276 0.34
   Stage I–III Ki-67 (%, continuous) 1.014 0.995–1.034 0.15

The model was restricted to four pre-specified covariates [weight variation, molecular subtype, TNM stage group (I–II vs. III), and Ki-67] based on the 10:1 events-per-variable rule (51 DFS events). CI, confidence interval; DFS, disease-free survival; HER2, human epidermal growth factor receptor 2; HR, hazard ratio; Lum A, luminal A; Lum B, luminal B; OS, overall survival; TN, triple negative; TNM, tumor-node-metastasis.

When analyzed categorically, patients with ≥5% weight loss had higher rates of disease recurrence and mortality compared to those with stable weight or weight gain (Table 5).When restricted to non-metastatic patients (stages I–III) who received neoadjuvant or adjuvant chemotherapy (n=134), the association between weight loss and worse DFS was maintained. Patients with ≥5% weight loss exhibited higher rates of disease recurrence (39.6%) compared to those with stable weight (15.5%) or weight gain (14.3%) (Table S3). These findings are consistent with the overall cohort and support the robustness of the observed relationship, although this subgroup analysis should be interpreted with caution due to limited statistical power. Weight change during chemotherapy by treatment setting (neoadjuvant vs. adjuvant) is detailed in Tables S4,S5.

Table 5

Distribution of non-metastatic patients (stages I–III, n=169) by weight change category

Weight category N (%) No recurrence, n (%) DFS events, n (%) Deaths, n (%)
Weight loss ≥5% 61 (36.1) 39 (63.9) 22 (36.1) 17 (27.9)
Stable weight ±5% 73 (43.2) 63 (86.3) 10 (13.7) 8 (11.0)
Weight gain ≥5% 35 (20.7) 28 (80.0) 7 (20.0) 3 (8.6)

DFS, disease-free survival.

Correlation between inflammatory markers and weight variation

Baseline inflammatory marker data were incomplete. CRP, ALC, NLR and PLR data were available for only a limited subset within the predefined baseline window, whereas weight data were available for most patients. Due to the high degree of missingness in inflammatory markers (Table S6), formal multivariable analyses were not performed. An exploratory correlation between leukocyte count and continuous NLR is presented in Figure S5 and should be interpreted with caution given variability in the timing of laboratory assessments.

In the analysis including all available patients, a weak but statistically significant inverse correlation was observed between baseline neutrophil count and weight variation as percentage change (Spearman rho =−0.244; P=0.01; n=98) and as absolute weight change in kg (rho =−0.250; P=0.01). Higher neutrophil counts were associated with greater weight loss. No other inflammatory markers showed significant correlations with weight variation.

In analyses restricted to non-metastatic patients (stages I–III), weak but statistically significant positive correlations were observed between percentage weight variation and absolute neutrophil count (r=0.2035; P=0.01), total leukocyte count (r=0.1875; P=0.02), and continuous NLR (r=0.1654; P=0.041). In exploratory analyses, simple (unadjusted) linear regression models were performed within pre-specified subgroups to assess the association between inflammatory markers (neutrophil count, leukocyte count, and continuous NLR) and percentage weight variation. No statistically significant associations were observed in any subgroup (Table S7). These findings should be interpreted with caution given the limited sample size and missing data.


Discussion

This retrospective cohort study provides real-world evidence regarding the complex interplay between weight dynamics, systemic inflammation, and oncological outcomes in women treated for breast cancer at a public institution in Brazil. Our primary finding indicates that weight variation during treatment is a significant prognostic factor for DFS, particularly among patients with non-metastatic disease (stages I–III).

We observed that patients who maintained a stable weight or experienced weight gain during treatment had a significantly lower risk of disease recurrence compared to those who lost weight. In the categorical analysis, patients with ≥5% weight loss had higher rates of disease recurrence (36.1%) compared to those with stable weight (13.7%) or weight gain (20.0%), supporting that the observed effect of weight variation is primarily driven by the weight-loss group (Table 4). For every percentage point of weight preserved or gained in the non-metastatic setting, the risk of recurrence decreased by approximately 5% in multivariate analysis adjusted for molecular subtype, TNM stage group (I/II vs. III), and Ki-67. This finding aligns with a growing body of literature suggesting that while obesity at diagnosis is a negative risk factor, weight loss during active therapy is often detrimental (11,22,23). Unintentional weight loss in this context is frequently a surrogate marker for treatment toxicity, poor nutritional intake, or cancer cachexia (24-27). Conversely, the ability to maintain weight may reflect better physiological resilience and tolerance to therapeutic regimens (24,27). Importantly, this association remained consistent in a subgroup analysis restricted to patients receiving neoadjuvant or adjuvant chemotherapy, in which a similar directional relationship between weight loss and worse prognosis was observed. It is crucial to note that our study used BMI and total weight, which do not differentiate between muscle and fat mass (11,23).

In our univariate analysis restricted to non-metastatic patients, we found weak but statistically significant positive correlations between weight balance and both absolute neutrophil count and NLR. However, these associations disappeared in multivariable linear regression models adjusted for confounders. This counterintuitive finding should be interpreted with caution: the weak effect size (Spearman rho =0.23) and the lack of consistent associations in exploratory analyses suggest that this relationship may reflect confounding by tumor burden, treatment intensity, or corticosteroid use, rather than a direct biological mechanism. We caution against over-interpreting this unadjusted correlation.

While elevated NLR and PLR are widely recognized as markers of poor prognosis in various meta-analyses (18-20), they did not emerge as significant predictors in our Cox regression models for non-metastatic patients. This may be attributed to the relatively modest sample size, the heterogeneous nature of treatments received, or the overshadowing influence of established prognostic factors. Importantly, with baseline inflammatory marker data available for only 8.1% of patients, formal multivariable testing of NLR and PLR was not feasible, and their independent prognostic value could not be adequately assessed; all conclusions regarding these markers should therefore be considered exploratory. Furthermore, the absence of longitudinal inflammatory measurements represents a key limitation, as baseline values do not allow assessment of dynamic changes over time, precluding inference of temporal or mechanistic relationships between systemic inflammation and weight variation.

From a clinical perspective, routine weight monitoring throughout oncological treatment is a simple, non-invasive tool to identify patients at risk. Clinicians should distinguish treatment-related weight loss (correlates temporally with chemotherapy cycles, may be reversible with antiemetic optimization and nutritional support) from cancer-associated cachexia (progressive, associated with systemic inflammation, anorexia, and muscle wasting). Early referral to clinical nutrition services and, where available, exercise oncology programs should be considered for patients experiencing significant weight loss (≥5%) during treatment (24,27).

The results of this study must be interpreted considering its limitations, primarily inherent to its retrospective observational design. Data collection relied on electronic medical records, leading to missing data points for some laboratory and anthropometric parameters. Specifically, baseline inflammatory marker data (NLR/PLR/ALC) was available for only 15/184 patients (8.1%) and CRP for only 5/184 patients (2.7%), severely limiting the ability to test their independent prognostic value. A formal a priori power calculation was not performed; with 51 DFS events in 169 non-metastatic patients, the study has approximately 80% power to detect a HR of ≤0.92 per unit change in weight variation at alpha =0.05. Weight variation was computed using the first and last available measurements, which may not fully capture the trajectory of weight change. We also acknowledge that reverse causation cannot be fully excluded: weight loss immediately preceding detected recurrence may partly reflect underlying disease activity. The lack of precise body composition data limits our ability to distinguish between muscle loss (sarcopenia) and fat loss. Furthermore, the single-center nature of the study may limit generalizability. The high rates of overweight (38.2%) and obesity (45.5%) observed in our cohort are consistent with the high prevalence of excess body weight in the Brazilian adult population, where obesity has been estimated at approximately 20% in population-based studies (28), although the proportion observed in our sample was higher, likely reflecting the specific clinical and demographic characteristics of this cohort.

Despite these limitations, the study reflects the real-world scenario of breast cancer care in the Brazilian public health system, including patients often excluded from clinical trials due to comorbidities.


Conclusions

Weight variation during treatment may be a valuable, easily obtainable clinical prognostic marker in non-metastatic breast cancer. Preventing significant weight loss during therapy should be a priority in supportive care. While inflammatory markers showed associations with metabolic status in univariate analyses, their formal independent prognostic role could not be tested due to data limitations and requires clarification in larger, prospective studies. Integrating nutritional surveillance into routine oncological practice could help identify high-risk patients who might benefit from early supportive interventions. These findings should be prospectively validated in larger, multicenter studies with standardized weight measurement protocols and formal a priori power calculations.


Acknowledgments

None.


Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://abs.amegroups.com/article/view/10.21037/abs-2026-1-0005/rc

Data Sharing Statement: Available at https://abs.amegroups.com/article/view/10.21037/abs-2026-1-0005/dss

Peer Review File: Available at https://abs.amegroups.com/article/view/10.21037/abs-2026-1-0005/prf

Funding: This study was supported by a research scholarship from the Brazilian National Council for Scientific and Technological Development (CNPq, Brazil; No. 147483/2025-5). The funding agency had no role in the study design, data collection, analysis, interpretation, or manuscript preparation.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://abs.amegroups.com/article/view/10.21037/abs-2026-1-0005/coif). A.d.G. serves as an unpaid editorial board member of Annals of Breast Surgery from May 2025 to December 2026. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Research Ethics Committee of Centro Universitário FMABC (CAAE: 86344925.0.0000.0082) and informed consent was waived due to the retrospective nature of the study.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.


References

  1. Bray F, Laversanne M, Sung H, et al. Global cancer statistics 2022: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin 2024;74:229-63. [Crossref] [PubMed]
  2. Lima MS, Siqueira HFF, Moura AR, et al. Temporal trend of cancer mortality in a Brazilian state with a medium Human Development Index (1980-2018). Sci Rep 2020;10:21384. [Crossref] [PubMed]
  3. Early Breast Cancer Trialists' Collaborative Group (EBCTCG). Effects of chemotherapy and hormonal therapy for early breast cancer on recurrence and 15-year survival: an overview of the randomised trials. Lancet 2005;365:1687-717. [Crossref] [PubMed]
  4. Berry DA, Cronin KA, Plevritis SK, et al. Effect of screening and adjuvant therapy on mortality from breast cancer. N Engl J Med 2005;353:1784-92. [Crossref] [PubMed]
  5. Hanahan D. Hallmarks of Cancer: New Dimensions. Cancer Discov 2022;12:31-46. [Crossref] [PubMed]
  6. Iyengar NM, Hudis CA, Dannenberg AJ. Obesity and inflammation: new insights into breast cancer development and progression. Am Soc Clin Oncol Educ Book 2013;33:46-51. [Crossref] [PubMed]
  7. Ruggieri L, Moretti A, Berardi R, et al. Host-Related Factors in the Interplay among Inflammation, Immunity and Dormancy in Breast Cancer Recurrence and Prognosis: An Overview for Clinicians. Int J Mol Sci 2023;24:4974. [Crossref] [PubMed]
  8. Castro-Espin C, Cairat M, Navionis AS, et al. Prognostic role of pre-diagnostic circulating inflammatory biomarkers in breast cancer survival: evidence from the EPIC cohort study. Br J Cancer 2024;131:1496-505. [Crossref] [PubMed]
  9. Kolb R, Sutterwala FS, Zhang W. Obesity and cancer: inflammation bridges the two. Curr Opin Pharmacol 2016;29:77-89. [Crossref] [PubMed]
  10. Bradshaw PT. Body composition and cancer survival: a narrative review. Br J Cancer 2024;130:176-83. [Crossref] [PubMed]
  11. Chan DSM, Vieira AR, Aune D, et al. Body mass index and survival in women with breast cancer-systematic literature review and meta-analysis of 82 follow-up studies. Ann Oncol 2014;25:1901-14. [Crossref] [PubMed]
  12. Lauby-Secretan B, Scoccianti C, Loomis D, et al. Body Fatness and Cancer--Viewpoint of the IARC Working Group. N Engl J Med 2016;375:794-8. [Crossref] [PubMed]
  13. Makari-Judson G, Judson CH, Mertens WC. Longitudinal patterns of weight gain after breast cancer diagnosis: observations beyond the first year. Breast J 2007;13:258-65. [Crossref] [PubMed]
  14. Vance V, Mourtzakis M, McCargar L, et al. Weight gain in breast cancer survivors: prevalence, pattern and health consequences. Obes Rev. 2011;12:282-94. [Crossref] [PubMed]
  15. Ligibel JA, Alfano CM, Courneya KS, et al. American Society of Clinical Oncology position statement on obesity and cancer. J Clin Oncol 2014;32:3568-74. [Crossref] [PubMed]
  16. Martin L, Senesse P, Gioulbasanis I, et al. Diagnostic criteria for the classification of cancer-associated weight loss. J Clin Oncol 2015;33:90-9. [Crossref] [PubMed]
  17. Grivennikov SI, Greten FR, Karin M. Immunity, inflammation, and cancer. Cell 2010;140:883-99. [Crossref] [PubMed]
  18. Templeton AJ, McNamara MG, Šeruga B, et al. Prognostic role of neutrophil-to-lymphocyte ratio in solid tumors: a systematic review and meta-analysis. J Natl Cancer Inst 2014;106:dju124. [Crossref] [PubMed]
  19. Zhou X, Du Y, Huang Z, et al. Prognostic value of PLR in various cancers: a meta-analysis. PLoS One 2014;9:e101119. [Crossref] [PubMed]
  20. Ethier JL, Desautels D, Templeton A, et al. Prognostic role of neutrophil-to-lymphocyte ratio in breast cancer: a systematic review and meta-analysis. Breast Cancer Res 2017;19:2. [Crossref] [PubMed]
  21. Zhao Z, Xu H, Ma B, et al. Prognostic value of platelet to lymphocyte ratio (PLR) in breast cancer patients receiving neoadjuvant therapy: a systematic review and meta-analysis. Front Immunol 2025;16:1658571. [Crossref] [PubMed]
  22. Chen X, Lu W, Zheng W, et al. Obesity and weight change in relation to breast cancer survival. Breast Cancer Res Treat 2010;122:823-33. [Crossref] [PubMed]
  23. Protani M, Coory M, Martin JH. Effect of obesity on survival of women with breast cancer: systematic review and meta-analysis. Breast Cancer Res Treat 2010;123:627-35. [Crossref] [PubMed]
  24. Prado CM, Baracos VE, McCargar LJ, et al. Body composition as an independent determinant of 5-fluorouracil-based chemotherapy toxicity. Clin Cancer Res 2007;13:3264-8. [Crossref] [PubMed]
  25. Fearon K, Strasser F, Anker SD, et al. Definition and classification of cancer cachexia: an international consensus. Lancet Oncol 2011;12:489-95. [Crossref] [PubMed]
  26. Argilés JM, Busquets S, Stemmler B, et al. Cancer cachexia: understanding the molecular basis. Nat Rev Cancer 2014;14:754-62. [Crossref] [PubMed]
  27. Martin L, Birdsell L, Macdonald N, et al. Cancer cachexia in the age of obesity: skeletal muscle depletion is a powerful prognostic factor, independent of body mass index. J Clin Oncol 2013;31:1539-47. [Crossref] [PubMed]
  28. Garcia CAB, Meira KC, Souza AH, et al. Obesity and Associated Factors in Brazilian Adults: Systematic Review and Meta-Analysis of Representative Studies. Int J Environ Res Public Health 2024;21:1022. [Crossref] [PubMed]
doi: 10.21037/abs-2026-1-0005
Cite this article as: Xande JG, de Alcantara Sousa LV, Jesus NAS, Brenna MF, Maselli-Schoueri JH, del Giglio A. Weight loss during treatment is associated with reduced disease-free survival in non-metastatic breast cancer. Ann Breast Surg 2026;10:10.

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