Prognostic significance of body fat in early-stage breast cancer.

Abstract

e12737 Background: Body fat is increasingly recognized as a key determinant of cancer biology and clinical outcomes. Although obesity is generally associated with poorer outcomes, the obesity paradox suggests a potential survival advantage in obese patients. While this phenomenon has been reported in several malignancies, its relevance in early-stage breast cancer remains unclear. Therefore, this study aimed to evaluate the prognostic impact of body fat in early-stage breast cancer. Methods: This retrospective cohort study included 134 female patients with early-stage breast cancer who presented between January 2018 and January 2020. Fat mass (FM) was assessed at the time of diagnosis using a Tanita Body Composition Analyzer. A fat mass cut-off value of 35%, determined as optimal by receiver operating characteristic (ROC) analysis, was examined for its association with survival outcomes. Results: The median age at diagnosis was 47 years (range 23–77), and 62.7% of patients were premenopausal. Median FM value at diagnosis were 35.5%. A FM cut-off of 35% was determined, with 70% sensitivity and 60% specificity [AUC:0.344, 95% CI:0.242–0.446, p=0.009]. Patients with baseline FM >35% had a mean event-free survival (EFS) of 99 months and mean overall survival (OS) of 104 months, while those with FM ≤35% had a mean EFS of 75 months and mean OS of 82 months. In multivariate analysis, estrogen receptor (ER) positivity (p=0.021), higher T stage (p=0.024), N3 disease (p=0.002), and baseline FM >35% (p<0.001) were independently associated with EFS. Similarly, ER positivity (p=0.015), higher T stage (p=0.006), N3 disease (p=0.040), and baseline FM >35% (p<0.001) were independent predictors of OS (Table). Conclusions: In our study, advanced tumor stage and N3 disease were associated with worse survival whereas ER positivity and baseline fat mass >35% were linked to improved EFS and OS. These findings suggest that baseline fat mass may serve as an independent prognostic factor in this patient population consistent with the obesity paradox. While this phenomenon has been reported in several cancer types, its relevance in early-stage breast cancer remains unclear and warrants further investigation. Multivariate Analyses of Event-Free Survival and Overall Survival. EFS OS HR 95% CI P value HR 95% CI P value ER status (Negative* vs Positive) 0.38 0.17-0.86 0.021 0.25 0.08-0.76 0.015 Clinical T stage (T1-2* vs T3-4) 2.54 1.12-5.73 0.024 5.16 1.59-16.65 0.006 Clinical N stage N0* Reference 0.017 Reference 0.07 N1 1.86 0.57-6.03 0.30 2.16 0.54-8.65 0.27 N2 2.31 0.74-7.22 0.14 0.95 0.23-3.93 0.94 N3 9.17 2.12-38.01 0.002 6.10 1.08-34.48 0.04 Fat Mass initially (%) (≤35* vs >35) 0.21 0.09-0.48 <0.001 0.41 0.008-0.20 <0.001 HR: Hazard Ratio; CI: Confidence Interval; ER: Estrogen Receptor; (*): Reference category.