Survivors of early-stage breast cancer who participated in a lifestyle intervention on healthy habits lost weight and experienced higher rates of disease-free survival if they completed the program, according to results presented at the 2018 San Antonio Breast Cancer Symposium, held Dec. 4–8.

"Evidence has shown that obesity and low physical activity are associated with higher risks of developing breast cancer, as well as an increased risk of recurrence and reduced survival," said the study's lead author, Wolfgang Janni, MD, chair of the Department of Obstetrics and Gynecology, University of Ulm, Germany.

"Many breast cancer survivors would like to contribute actively to improving their prognosis, and guiding them on lifestyle factors that can help them control weight is one possible way to positively impact patient outcomes," he continued.

Dr. Janni and colleagues studied a telephone-based lifestyle intervention as part of a larger phase 3 study, the SUCCESS C study, which compared disease-free survival in patients with HER2-negative early-stage breast cancer who were treated with one of two chemotherapy regimens.

In the lifestyle intervention part of the study, researchers enrolled 2,292 of the 3,643 women who were already participating in the SUCCESS C trial. All had a body mass index of 24 or higher. The women were randomly assigned to receive either telephone-based, individualized guidance aimed at helping them achieve moderate weight loss for 2 years, or general recommendations for a healthy lifestyle alone. Those who received the telephone calls were given advice on how to improve their diets, lower fat intake, increase physical activity, and other tips that were geared to their specific needs.

At the end of the two-year follow-up period, patients in the lifestyle intervention arm had lost an average of 1.0 kilogram (2.2 pounds), while the patients in the control group had gained an average of 0.95 kilograms. In the intention to treat analysis, there was no difference in survival between patients who were assigned to the lifestyle intervention compared to the standard arm.

Overall, 1,477 patients completed the lifestyle intervention. Those who completed the program had a 35% higher rate of disease-free survival than those who began the program but did not complete it.

Among those who completed the program, those who received the lifestyle intervention were about 50% more likely to have disease-free survival than those who received the general recommendations. The improved outlook was similar in both univariable analysis and when the researchers controlled for factors such as age, menopausal status, tumor size, hormone receptor status, and chemotherapy type.

Janni said that while the exploratory analysis should be interpreted with caution, this study indicates that completion of a systematic telephone lifestyle intervention program may positively affect outcomes for patients diagnosed with early-stage breast cancer.

"Lifestyle intervention might improve the prognosis of breast cancer patients if adherence is high," Janni said. "This was a highly feasible program to design and implement, and further studies are warranted to confirm its effectiveness." He said future research could include additional subgroup analysis and could examine whether the improved outlook for disease-free survival also correlates with certain biomarkers.

Dr. Janni cautioned that the most significant factors affecting disease-free survival are tumor stage and tumor biology. He said a limitation of this study is that the patients who chose to complete the lifestyle intervention may have already been more motivated to improve their fitness.

This study was funded by Chugai, Glaxo Smith Kline, Janssen Diagnostics, Pfizer, and Sanofi-Aventis. Dr. Janni declares no conflicts of interest.