Use of Dietary Supplements at a Comprehensive Cancer Center.

Objectives: The objectives of this study were to define dietary supplement (DS) use by cancer patients and to investigate factors associated with DS use during cancer treatment.

Methods: A cross-sectional survey of adults diagnosed with breast, colorectal, lung, or prostate cancer in 2010-2012 at the University of North Carolina Comprehensive Cancer Center was conducted. Questionnaires were sent to 1794 patients. Phone calls were made to nonrespondents. The authors described type of DS use before, during, and after initial cancer treatment, source of advice on DS use, and used logistic regression to investigate the association of DS use during or after cancer treatment with clinical/sociodemographic characteristics and source of advice.

Results: Six hundred and three (34%) patients completed the questionnaires. Nonvitamin nonmineral DS use during initial cancer treatments was common: any cancer treatment (49%), chemotherapy (52%), and radiation therapy (51%). Among patients seeking advice on DS use, 75% reported professional sources, 44% reported media sources, and 47% reported lay sources. DS use during cancer treatment was strongly predicted by prior DS use, followed by prior complementary therapies' use, receiving DS advice from a cancer care provider, being female, and higher education level.

Conclusion: DS use is common and persists during cancer treatment. Among DS users during treatment, 18% used an herbal supplement, which are likely to carry greater risk of interaction with chemotherapy agents compared with vitamin, mineral, and other supplements. Although many respondents sought DS advice from professional sources, the use of nonprofessional sources remains high.