Associations of non-melanoma skin cancer and melanoma, extra-cutaneous cancers and smoking in adults: A US population-based study

Background Non-melanoma skin cancer (NMSC) and melanoma are common malignancies in the US and may be associated with other types of cancer. Objectives We sought to determine whether NMSC and melanoma are associated with extra-cutaneous cancers and identify modifiable risk factors for such an association. Methods We analysed data from 447 801 adult participants in the 1997-2011 National Health Interview Surveys. Survey logistic regression models were constructed that accounted for the complex sample weights. History of NMSC, melanoma and 27 primary extra-cutaneous cancers was assessed. Results NMSC was associated with increased odds of one (multinomial survey logistic regression, unadjusted odds ratio [95% CI]: 2.43 [2.20-2.68]) or multiple (2.94 [2.21-3.92]) extra-cutaneous malignancies. Melanoma was also associated with increased odds of one (3.25 [2.70-3.90]) or multiple (6.11 [4.34-8.61]) extra-cutaneous malignancies. Extra-cutaneous cancers were more common in younger patients (ages 18-39 and 40-49 years) and Caucasians with NMSC or melanoma (P < 0.0001). Smokers with a history of NMSC or melanoma had even higher odds of extra-cutaneous malignancy at ages 18-39 and 40-49 years compared to smokers without NMSC or melanoma (P < 0.0001). History of NMSC was associated with higher odds of malignancies of the bladder, brain, breast, colon, oesophagus, kidney, lung, lymphoma, melanoma, prostate, soft tissue, throat/pharynx, thyroid and uterus. Melanoma was associated with malignancies of the bladder, breast, colon, kidney, lung, pancreas, prostate, soft tissue, throat/pharynx, thyroid and uterus. The prevalence of extra-cutaneous cancers increased between 1997 and 2011 in all subjects (4.51% and 5.73%, P < 0.0001), with even higher rates of increase in those with history of NMSC or melanoma. Conclusions Patients with history of NMSC and melanoma have increased odds of developing extra-cutaneous cancers, especially those with younger age and smoking history.