Epidemiology of nonmelanoma skin cancer in Japan: Occupational type, lifestyle, and family history of cancer.

Skin cancer is the most frequently diagnosed cancer in the fair-skinned population. In recent years, the incidence of nonmelanoma skin cancer (NMSC) has been increasing worldwide. However, there is no epidemiological study on skin cancer in the Asian population. A prospective cohort study including 140 420 participants was initiated in 1990 for cohort Ⅰ and 1993 for cohort Ⅱ at baseline survey from 11 public health center (PHC) areas. Of these participants, 284 NMSC cases were diagnosed during the follow-up period (through 2012 in the Osaka PHC area and 2013 in the other PHC areas). The Cox proportional hazards model was used to estimate hazard ratios and 95% confidence intervals (CI) for NMSC incidence according to occupational type, lifestyle factors (alcohol consumption, coffee consumption, smoking status, physical activity, and body mass index), and family history of cancer. Among men, compared with indoor workers, outdoor workers were associated with 2.18 (95% CI, 1.17-4.04) higher risk of squamous cell carcinoma (SCC) but not of basal cell carcinoma (BCC). Furthermore, men who have a family history of cancer had 1.99 (95% CI, 1.10-3.62) higher SCC risk. In women, we did not observe any association between occupational type and the risk of SCC (1.26; 95% CI, 0.68-2.32) or BCC (0.74; 95% CI, 0.42-1.28). In conclusion, men who are outdoor workers or have a family history of cancer had an increased risk of SCC.