Risk of second primary cancer and death following a diagnosis of nonmelanoma skin cancer.

Cancer-free patients diagnosed with a first primary nonmelanoma skin cancer (NMSC) offer an opportunity for studying the risk of a second primary cancer without the confounding effect of systemic treatment. The objective of the study was to estimate the risk of second primary cancer in people with a history of basal cell carcinoma (BCC) or squamous cell carcinoma (SCC) and the risk of dying in cancer patients with a NMSC history. BCC and SCC cases diagnosed between 1956 and 2000 in Manitoba, Canada were followed-up for second primaries (other than NMSC). Standardized incidence and mortality ratios (SIR and SMR) were calculated. Men [SIR, 1.06; 95% confidence interval (95% CI), 1.02-1.10] and women (SIR, 1.07; 95% CI, 1.02-1.12) with a BCC history as well as men (SIR, 1.15; 95% CI, 1.08-1.22) with a SCC history were at greater risk of a second primary cancer. Overall, the increased risk was observed only in the first 4 years following a NMSC, although it remained increased for specific cancer sites. The risk remained higher in all age groups up to 75 years of age. People with a history of BCC (males: SMR, 1.09; 95% CI, 1.04-1.14; females: SMR, 1.24; 95% CI, 1.16-1.32) or SCC (males: SMR, 1.18; 95% CI, 1.09-1.27; females: SMR, 1.55; 95% CI, 1.35-1.79) had a greater risk of death following their second primaries. Even if NMSC patients are at greater risk of a second cancer, it is not recommended to follow them up beyond the generally accepted periodic examination of the skin.