Longitudinal patterns and associated factors of postdiagnosis weight changes in Korean breast cancer survivors with normal body mass index.

PURPOSE: This study aimed to describe longitudinal patterns of weight changes from diagnosis to within 5 years after diagnosis and investigate factors associated with short- and long-term weight changes among Korean breast cancer survivors with initially normal body mass index (BMI).

METHODS: Body weights at diagnosis for 1546 breast cancer survivors were compared with those at 12, 24, 36, 48, and 60 months after diagnosis. Absolute weight change (kg) and relative weight changes (%) were analyzed. Logistic regression was used to identify factors associated with short-term (1 year) and long-term (5 years) weight changes.

RESULTS: A significant decrease in mean weight was predominant at 12 months postdiagnosis. In subgroup analysis, the younger age group showed significant weight gains after 36 months. The older age group and chemotherapy (CT) group showed significant weight losses after 24 months. About 40% of weight gainers and 60% of weight losers at 12 months returned to their initial weight by 60 months postdiagnosis. CT and lower educational levels were associated with short-term weight loss and gain, respectively. For long-term changes, age at diagnosis was the sole associated factor.

CONCLUSIONS: Korean breast cancer survivors treated with CT mainly experienced postdiagnosis weight loss rather than weight gain. Short-term weight change was independently associated with chemotherapy and educational level. However, long-term weight change was associated with age at diagnosis. Breast cancer survivors with normal BMI may be categorized according to the time-dependent risk for postdiagnosis weight change.