Following such recommendations surrounding smoking, physical activity (PA), eating fruits and vegetables and reducing or eliminating sugar-sweetened beverages seemed to be the most beneficial, wrote the authors of the paper published online in JAMA Network Open.
Rikki A. Cannioto, PhD, EdD, with the department of cancer prevention & control, Roswell Park Comprehensive Cancer Center in Buffalo, N.Y., led the prospective cohort study of 1,340 patients.
The American Institute for Cancer Research and American Cancer Society regularly recommend and publish lifestyle modifications for cancer prevention. To conduct this study Dr. Cannioto and colleagues developed an aggregate lifestyle scoring index to investigate whether those recommendations have an effect on high-risk breast cancer survival.
Highest adherence vs. lowest cut death risk by more than half
The researchers found patients with highest vs. lowest lifestyle index scores saw a 37% reduction in cancer recurrence (hazard ratio, 0.63; 95% confidence interval, 0.48-0.82) and a 58% reduction in mortality (HR, 0.42; 95% CI, 0.30-0.59).
“As a person who has based her career on the belief that our modifiable lifestyle behaviors are associated with cancer survival, I was actually surprised about how strong these associations were, especially for breast cancer recurrence,” Dr. Cannioto said in an interview,
The author also expressed surprise about the associations that were seen “in patients diagnosed with triple-negative breast cancer and HER2-positive breast cancer, which are the two subtypes traditionally more aggressive and more difficult to treat.”
Most patients in the study were diagnosed with hormone receptor–positive breast cancer (873 [65.3%]); completed some education beyond high school (954 [71.2%]); were postmenopausal (696 [52.5%]); and self-identified as non-Hispanic White (1,118 [83.7%]).
Patients were drawn from the Diet, Exercise, Lifestyles, and Cancer Prognosis (DELCaP) study, a prospective, observational cohort study ancillary to a multicenter phase 3 trial led by the Southwest Oncology Group (SWOG). The DELCaP study was designed to examine lifestyles before diagnosis, during treatment, and at 1 and 2 years after treatment.
Never smoking, physical activity had strongest links
Never smoking and meeting or exceeding PA guidelines had the strongest and most consistent associations with outcomes; each factor was linked with a 44%-45% reduced risk of mortality and a 35% reduced risk of recurrence.
Strongest adherence to the alcohol and body mass index (BMI) recommendations were not significantly associated with improved outcomes.
Partial and full adherence to red and processed meat recommendations were associated with significant reductions in mortality, but not recurrence.
The authors note that, while medications are the foundation for breast cancer treatment, lifestyle interventions could be a safe and inexpensive additional strategy for delaying and preventing recurrence and death.
“Such developments could be especially impactful for patients diagnosed with more aggressive tumors that do not respond well to current therapies,” they write.
Dr. Cannioto says the guidelines around physical activity advise 150 minutes or more of moderate to vigorous intensity a week. But she noted that this research shows that any physical activity can lead to longer survival.
“The greatest benefits from physical activity occur from moving from a sedentary lifestyle to beginning to be active,” she said.
Dr. Cannioto acknowledged the homogeneity of the study population as a limitation and recommended the associations next be tested in a more racially and ethnically diverse population of breast cancer patients.
This work was supported by the National Cancer Institute, the Breast Cancer Research Foundation, and Amgen.
The authors report receiving grants from the Southwest Oncology Group and the National Cancer Institute during the conduct of the study and receiving personal fees, grants, or serving on the boards or independent monitoring committees of many pharmaceutical companies. A full list of disclosures is available with the paper.