Body mass index and weight changes in patients with HER2-positive early breast cancer: A sub-analysis of the APHINITY trial.

BACKGROUND

Body mass index (BMI) may affect prognosis in patients with breast cancer (BC). We assessed the association of BMI and weight changes with outcomes of patients with HER2-positive early BC included in the APHINITY trial.

METHODS

This is an exploratory analysis of APHINITY (NCT01358877), randomized trial testing adjuvant dual vs. single HER2 blockade plus chemotherapy in HER2-positive early BC. BMI was collected at baseline and at two years after randomization. Patients were classified as underweight/normal weight (BMI<25 kg/m2) and overweight/obese (BMI≥25 kg/m2). The association of BMI with invasive disease-free survival (iDFS), distant recurrence-free interval (DRFI) and overall survival (OS) was investigated. Landmark approach was used to compare event for weight change ≥ 5.0 % at 2 years from baseline.

RESULTS

Of 4787 patients included, 2252 (47 %) were overweight/obese and 2535 (53 %) underweight/normal weight. Patients who were overweight/obese had more often chemotherapy discontinuation compared to underweight/normal weight patients (14 % vs. 9 %, p < 0.001). Patients who were overweight/obese exhibited worse iDFS (adjusted hazard ratio [aHR] 1.27; 95 % CI 1.06-1.52), DFRI (aHR 1.32; 95 % CI 1.06-1.64) and OS (aHR 1.38; 95 %CI 1.08-1.77) than underweight/normal weight patients. This effect on iDFS remained after adjusting for chemotherapy discontinuation (iDFS aHR 1.26, 95 % CI 1.05-1.51; DRFI aHR 1.31, 95 % CI 1.06-1.63; OS aHR 1.35 95 % CI 1.05-1.73). Weight changes at 2 years were not associated with clinical outcomes.

CONCLUSIONS

Our exploratory findings suggest that overweight/obesity at diagnosis was associated with worse survival outcomes.