OBJECTIVES: We estimated prevalence of complementary and alternative medicine (CAM) use by reason for use (treatment, wellness, or both) among non-institutionalized adults with cancer in the United States. We also examined health-related quality of life (HRQOL) outcomes among adults with cancer who used CAM. METHODS: We used data from the 2012 National Health Interview Survey (NHIS), which represents non-institutionalized adults with cancer (n = 2967 unweighted). Using a cross-sectional design with survey sampling techniques, we estimated past year prevalence of CAM use. We ran multivariable logistic regression analyses to investigate the odds of perceived benefits of CAM. RESULTS: In the past 12 months, 35.1% of adults with cancer reported using some form of CAM. Among CAM users, 56.0% used CAM for both treatment and wellness, and 32.4% used CAM for wellness only. Only 11.6% used CAM for treatment only. Regardless of reason for use, the most commonly used CAM types in the past year were herbal therapies (56.8%), chiropractic (27.1%), and massage (24.9%). Among CAM users, those using CAM for wellness only and for a combination of treatment and wellness reported significantly higher odds of "a better sense of controlling health" and "improved overall health and feeling better" compared with treatment only users. Similar patterns were found in other HRQOL outcomes, but they were not statistically different. CONCLUSIONS: CAM is widely used among adults with cancer for wellness only or a combination of treatment and wellness. Given improved HRQOL outcomes, CAM may be a promising approach for enhancing health promotion and well-being among adults with cancer.