Body Mass Index and Hormone Receptor Status Influence Recurrence Risk in HER2-Positive Early Breast Cancer Patients.

INTRODUCTION: A reliable risk stratification on the basis of tumor biology and host factors of HER2-positive (HER2+) early breast cancer (eBC) patients is needed. The aim of our study was to assess the prognostic role of body mass index (BMI) and hormone receptor (HR) expression in this setting.

PATIENTS AND METHODS: We retrospectively evaluated 238 women with stage I to III HER2+ breast cancer who completed adjuvant chemotherapy (CHT) and 1 year of treatment with trastuzumab. The end point was 3-year distant disease-free survival (3yDDFS). Survival analysis was evaluated using the Kaplan-Meier method. Multivariate analysis was performed using Cox proportional-hazards model adjusting for HR status, BMI, tumor staging, size, nodal status, and type of adjuvant CHT. Association among categorical variables was assessed using χ2 test.

RESULTS: The early recurrence rate after 3 years resulted as 4.2% (40% HR+ patients and 60% HR- patients). Neither HR status nor BMI alone showed an association with 3yDDFS in multivariate analysis. However, the hazard ratios for patients with HR- tumors who had also BMI ≥25 (3yDDFS 86.9%; 95% confidence interval [CI], 75.0%-97.7%) were amplified compared with patients with HR+ tumors and with BMI <25 (3yDDFS 98%; 95% CI, 94.8%-100.0%) and other subgroups (P = .003). This observation was confirmed in multivariate analysis (hazard ratio, 1.79; 95% CI, 1.04-3.07; P = .03).

CONCLUSION: Our real-life data highlight a different risk of eBC recurrence after grouping patients according to HR status and BMI. These results might help clinicians to identify correct treatment strategies. Patients who are HR- and have BMI ≥25 might benefit from escalation approaches, whereas those who are HR+ and have BMI <25 might be eligible for a shorter duration of adjuvant treatment with anti-HER2 agents.