Effect of a comprehensive lifestyle intervention program on body weight and health behavior in women with breast cancer: Results from a randomized controlled trial

Background: Both overweight/obesity and a Western lifestyle are associated with a poorer prognosis in women with breast cancer. The primary aim of this analysis was to examine the effect of a telephone-delivered lifestyle intervention program on reducing body weight and waist circumference, decreasing cardiovascular risk factors and improving lifestyle. Design: Data is derived from an open-label, randomized, controlled phase III study that evaluated two chemotherapy regimens and the impact of a 2-year lifestyle intervention on disease-free survival and secondary outcomes in women with intermediate-risk to high-risk breast cancer. Initially, 2292 women with a body mass index (BMI) between 24 and 40 kg/m² were randomized into one of two arms of the lifestyle intervention study. After accounting for dropout, 1785 participants remained: 776 in the intervention group (IG) who received a telephone-delivered lifestyle intervention supported by mailed materials, and 1009 in the low-level intervention group (LLIG) who received only mailed educational materials with general recommendations for a healthy lifestyle. Body weight, waist circumference, dietary intake, physical activity, and cardiovascular disease risk parameters were measured repeatedly throughout the intervention and a subsequent 2-year follow-up period. Linear mixed models for repeated measures were used to assess differences in study outcomes between the LLIG and IG at each measured time point. Results: IG participants showed a mean weight loss of −2.7 kg (kg) (versus +0.4 kg, LLIG) at 6 months, −2.8 kg (vs. +0.8 kg, LLIG) at 12 months and −1.8 kg at 24 months (versus +0.9 kg, LLIG). Significant between-group differences for weight loss and reduced waist circumference were observed at all time points until the end of the lifestyle intervention (all p-values < 0.0001), including post-intervention. Reduced energy intake and a higher alternate healthy eating index (AHEI) score in the IG was detected during the lifestyle intervention (AHEI at 24 months: IG 49.1% versus LLIG 42.0%, p < 0.001). Modest significant improvements in several cardiovascular risk factors were observed during the intervention, including fasting plasma glucose, HbA1c, systolic and diastolic blood pressure, and lipids. Conclusions: A mainly telephone-delivered lifestyle intervention program can reduce body weight and waist circumference, improve diet quality, and decrease cardiometabolic risk in women with overweight/obesity and newly diagnosed, human epidermal growth factor receptor 2 (HER2)/neu-negative, intermediate-risk to high-risk breast cancer. Weight loss, reduced waist circumference and improved dietary patterns were maintained for up to two years post-intervention. Trial registration: The protocol was registered under the EU Clinical Trials Register, https://www.clinicaltrialsregister.eu/, identifier: 2008-005453-38.