Complementary and Alternative Medicine Use, Cancer Screening, and Medical Checkups in Japan from 2001 to 2013: A Repeated Cross-Sectional Study

Introduction: The association between complementary and alternative medicine (CAM) use and other health-related behaviors is an important issue. A previous study reported that complementary medicine use is related to greater use of cancer screening, whereas alternative medicine use is related to lower use of cancer screening. Given the sparse evidence from Japan, we aimed to examine the association of CAM use with cancer screening and medical checkups. We used a repeated cross-sectional survey of a nationally representative sample of Japanese people and conducted age-period-cohort analysis.Methods: The study population was 68,217 of 83,827 individuals observed from 2001 to 2013 who received cancer screening. CAM users were defined as individuals who received acupuncture, moxibustion, anma/massage/shiatsu, or judo therapy for their most worrisome symptom. The outcomes of interest were receiving stomach, lung, colorectal, uterine, and breast cancer screenings and medical checkups. Using crossclassified multilevel logistic regression models, we estimated odds ratios (ORs) and 95% credible intervals (CIs) for cancer screening and medical checkups.Results: For CAM users of complementary medicine, the adjusted ORs for stomach, lung, and colorectal cancer screening were 1.40 (95% CI: 1.35-1.44), 1.37 (95% CI: 1.34-1.40), and 1.52 (95% CI: 1.49-1.54), respectively. We found similar results for uterine and breast cancer screening, and medical checkups.Conclusions: Irrespective of whether they use CAM, CAM users in Japan tend to receive a variety of cancer screenings and medical checkups.