Objectives: To estimate (1) the magnitude of and the components and factors associated with nonmelanoma skin cancer (NMSC) mortality and (2) the proportion of deaths misclassified as NMSC.
Design: Population-based follow-back study.
Setting and patients: All Rhode Island residents whose deaths between 1988 and 2000 were attributed to NMSC.
Main outcome measures: Distribution of diagnoses, verification of the causes of death, and characterization of associated factors.
Results: The proportion of misclassified deaths was significantly higher for nongenital NMSC (57%) than for genital NMSC (18%; P<.001). Most of the deaths misclassified as nongenital NMSC were caused by squamous cell carcinoma of mucosal surfaces. The age-adjusted NMSC mortality rate was 0.91 (per 100 000 persons per year), of which almost half (0.45) were due to genital carcinoma. Nonmelanoma skin cancer mortality increased sharply with age. The mortality rate from nongenital NMSC in men was more than twice that in women, but for genital NMSC this ratio was reversed. Skin cancers originating on the ear were responsible for more than a quarter of all deaths caused by nongenital NMSC. No cases of NMSC mortality occurred in organ transplant recipients. Many individuals had comorbid psychiatric conditions or evidence of unreasonable delay in seeking medical care for their lesions.
Conclusions: Misclassifying the cause of death as nongenital NMSC accounts for a large source of error on death certificates in Rhode Island. Overall, nongenital squamous cell carcinoma and basal cell carcinoma death rates have declined, and mortality due to genital carcinoma was about half of total NMSC deaths. The dermatology community should emphasize prevention of mortality from genital skin cancer, while continuing to stress the importance of reducing excessive exposure to UV light and prompt treatment of NMSC.