Risk of second cancers after the diagnosis of non-melanoma skin cancer in Korean patients.

Individuals with a personal history of non-melanoma skin cancer (NMSC) are known to have an increased risk of subsequent cancers. However, most of the studies regarding this fact were done on Caucasian populations. We investigated whether Korean patients with NMSC have an increased risk of developing second cancers compared to the general Korean population. Five hundred and thirty-two patients diagnosed with NMSC at the Department of Dermatology of Yonsei University Health System from 1999 to 2008 were assessed for development of second cancers. The overall second cancer incidence was increased among patients diagnosed with NMSC compared with the general population in Korea: 37 second cancer total (standardized incidence ratio [SIR] 1.38, 95% confidence interval [CI] 1.10-1.90); 23 second cancers in males (SIR 4.24, 95% CI 2.69-6.36); and 14 second cancers in females (SIR 2.28, 95% CI 1.25-3.83). There were significantly increased incidence ratios for NMSC (eight second cancers [SIR 9.52, 95% CI 4.11-18.77]), bladder cancer (four second cancers [SIR 4.21, 95% CI 1.15-10.78]) and nasopharyngeal cancer (one second cancer [SIR 20.00, 95% CI: 1.51-25.33]). Korean patients diagnosed with NMSC had more second cancers, particularly other skin cancers. This study provides additional evidence that NMSC may be a clinically significant and substantial risk factor for second cancers even in a Korean population, in which the incidence of NMSC is much lower than Caucasians.