We studied metabolic factors, diabetes, and anthropometric measurements at diagnosis and long-term follow-up (LTFU), mean 12.5 years post-diagnosis, in breast cancer (BC) survivors, and compared their status at LTFU to that of age-matched women without BC. Diet and physical activity were also assessed.
535 non-diabetic BC patients treated at three University of Toronto hospitals were followed prospectively; 285 surviving patients, without distant recurrence, participated in a LTFU study. A control group of 167 age-matched women without BC was recruited from a mammogram screening program at one of the hospitals. Change over time was analyzed using paired t tests, and comparisons between BC survivors and controls used age and education (AE)-adjusted regression models.
Median weight gain in BC survivors was 2.00 kg (p < 0.0001); BMI, glucose, insulin, homeostasis model assessment (HOMA), and total cholesterol increased modestly but significantly. Waist circumference, glucose, and triglycerides were higher in LTFU BC survivors versus controls. BC survivors had significantly greater prevalence of diabetes/pre-diabetes versus controls (33 vs. 20.4%, AE-adjusted odds ratio (OR) 1.59, p = 0.050). This effect was restricted to those with lower levels of physical activity (<56 metabolic equivalent (MET)-hours/week: OR 2.70 versus 0.94 for those with higher physical activity, interaction p = 0.034). At LTFU, BC survivors were more physically active than at diagnosis (median increase 28 MET-hours/week interquartile range −14.8 to 82), and compared to controls (median 68.2 vs. 44 MET-hours/week, p < 0.0001).
The prevalence of the metabolic syndrome and diabetes/pre-diabetes was significantly higher in BC survivors than in controls group, notably in those with lower levels of physical activity. Enhanced diabetes/metabolic syndrome screening and promotion of physical activity may be warranted in BC survivors.