Use of complementary and alternative medicine and breast cancer survival in the Health, Eating, Activity, and Lifestyle Study.

Purpose: Use of complementary and alternative medicine (CAM) is common among breast cancer patients, but less is known about whether CAM influences breast cancer survival.

Methods: Health Eating, Activity, and Lifestyle (HEAL) Study participants (n = 707) were diagnosed with stage I-IIIA breast cancer. Participants completed a 30-month post-diagnosis interview including questions on CAM use (natural products such as dietary and botanical supplements, alternative health practices, and alternative medical systems), weight, physical activity, and comorbidities. Outcomes were breast cancer-specific and total mortality, which were ascertained from the Surveillance Epidemiology and End Results registries in Western Washington, Los Angeles County, and New Mexico. Cox proportional hazards regression models were fit to data to estimate hazard ratios (HR) and 95 % confidence intervals (CI) for mortality. Models were adjusted for potential confounding by sociodemographic, health, and cancer-related factors.

Results: Among 707 participants, 70 breast cancer-specific deaths and 149 total deaths were reported. 60.2 % of participants reported CAM use post-diagnosis. The most common CAM were natural products (51 %) including plant-based estrogenic supplements (42 %). Manipulative and body-based practices and alternative medical systems were used by 27 and 13 % of participants, respectively. No associations were observed between CAM use and breast cancer-specific (HR 1.04, 95 % CI 0.61-1.76) or total mortality (HR 0.91, 95 % CI 0.63-1.29).

Conclusion: Complementary and alternative medicine use was not associated with breast cancer-specific mortality or total mortality. Randomized controlled trials may be needed to definitively test whether there is harm or benefit from the types of CAM assessed in HEAL in relation to mortality outcomes in breast cancer survivors.