Association of Obesity and Luminal Subtypes in Prognosis and Adjuvant Endocrine Treatment Effectiveness Prediction in Chinese Breast Cancer Patients.

PURPOSE

To evaluate the influence of obesity on clinicopathological characteristics of breast cancer; to explore the effect of obesity on the prognosis and performance of endocrine therapy in breast cancer patients.

METHODS

Patients with luminal/HER2-negative early breast cancer were included and categorized into the non-obese (BMI<28kg/m) and obese (BMI≥28kg/m) groups according to body mass index (BMI). Clinicopathological characteristics and treatment modalities were compared between groups. Interaction of adjuvant endocrine therapy with obesity was analyzed.

RESULTS

A total of 2,875 patients were included: 2,598 non-obese and 277 obese. A higher rate of patients with comorbidities (OR: 2.83, 95%CI 2.13-3.74, <0.001) or PR-positive tumor (OR: 1.63, 95%CI 1.03-2.58, =0.037) were identified in the obese group. Obesity was not associated with disease recurrence (=0.839) or overall survival (=0.140) in the whole population. Subgroup analysis did show an association with worse relapse-free survival (RFS, HR 3.48, 95%CI 1.31-9.22, =0.012) and overall survival (OS, HR 4.67, 95%CI 1.28-16.95, =0.019) in luminal A breast cancer. These results could not be reproduced in the luminal B subtype with a RFS (HR 0.78, 95%CI 0.41-1.49, =0.454) or OS (HR 1.17, 95%CI 0.50-2.74, =0.727). Furthermore, obesity did not impact endocrine therapy effectiveness in Tamoxifen or the aromatase inhibitor group (RFS: interact =0.381; OS: interact =0.888).

CONCLUSIONS

The impact of obesity on prognosis interacted with luminal subtype status in Chinese breast cancer patients which was not related with endocrine treatment modality.