Incidence of multiple primary cancers following respiratory tract cancer in Umbria, Italy.

Improvements in cancer survival and life expectancy have placed a focus on long-term risks following a primary cancer, including that of developing other primary malignancies. The purpose of this study was to evaluate the risk, in patients with respiratory tract cancers, of developing a second primary malignancy. Methods: Standardized incidence ratios (SIR) of observed to expected cases were calculated for residents of Umbria diagnosed with laryngeal and lung cancer between 1994 and 2008. Significance and 95% confidence intervals were determined assuming a Poisson distribution. Results: In total, 189 and 340 cases of second primary cancers were observed respectively among laryngeal and lung cancer patients. Male laryngeal cancer patients were found to have a significantly increased risk of lung cancer (SIR=4.10), non-melanoma skin cancer (SIR=2.10), bladder cancer (SIR=2.25) and pancreatic cancer (SIR=3.85). In females, a significantly increased risk was observed only when all sites combined were considered. Male lung cancer patients were found to have a significantly increased risk for laryngeal cancer (SIR=4.36), esophageal cancer (SIR=3.97), kidney cancer (SIR=3.40), multiple myeloma and malignant plasma cell neoplasm (SIR=2.97), bladder cancer (SIR=2.20) and non-melanoma skin cancer (SIR=1.55). In females, the risk of developing a second cancer was higher but was not significant for non-melanoma skin cancers, colon and breast cancer. Conclusions: Study results show an excess risk of other primary malignancies in respiratory tract cancer patients, particularly males. This may be due to shared risk factors, genetic susceptibility, effect of first cancer treatments and increased diagnostic surveillance.