Body Composition Analysis of 10 Years versus 5 Years of Adjuvant Endocrine Therapy in Patients with Nonmetastatic Breast Cancer

Objective Our study aims to investigate the association of extended adjuvant endocrine therapy with disease-free survival (DFS), muscle mass, muscle strength, and visceral adipose tissue in patients with nonmetastatic breast cancer and the effect of extended endocrine therapy on body composition. Patients and Methods . Patients ( N  = 90) with nonmetastatic breast cancer aged between 60 and 65 years old were prospectively recruited in this study, compromising a cohort of subjects rece iving 5 years or 10 years of adjuvant endocrine therapy. Patients' DFS was compared between these two groups. Patients' body composition including muscle and fat using CT scans, muscle strength, and gait speed was evaluated in these two groups.Results Dietary behavior was recorded with the food frequency questionnaire (FFQ). Patients' age, body weight, and body mass index (BMI) did not differ between the two groups. An extended adjuvant endocrine therapy into 10 years could translate into DFS benefit (123.8 vs. 102.2 months, P =0.038). Patients receiving 10 years of adjuvant endocrine therapy had less skeletal muscle and more visceral fat compared with patients receiving 5 years of adjuvant endocrine therapy. The skeletal muscle index was 50.3 ± 1.6 cm 2 /m 2 versus 46.5 ± 1.3 cm 2 /m 2 in the 10 years or 5 years of adjuvant endocrine therapy group ( P =0.042). The visceral fat was 28.9 ± 2.9 cm 2 /m 2 versus 55.0 ± 3.2 cm 2 /m 2 in the 10 years or 5 years of adjuvant endocrine therapy group ( P =0.011). The muscle strength, gait speed, and FFQ results in the two groups not reaching statistical difference.Conclusion In conclusion, breast cancer patients with 10 years of adjuvant endocrine therapy had DFS benefit, but with more muscle loss and adipose tissue deposits compared to patients receiving 5 years of adjuvant endocrine therapy.