Subsequent primary malignancies in patients with nonmelanoma skin cancer in England: a national record-linkage study.

BACKGROUND: Conflicting evidence exists about whether people with a history of nonmelanoma skin cancer (NMSC) are at higher risk of subsequent primary malignant cancers than those without. METHODS: An all England record-linked hospital and mortality dataset spanning from 1999 to 2011 was used. We constructed two cohorts: one that comprised people with a history of NMSC (502,490 people), and a control cohort that comprised people without. We "followed up" these two cohorts electronically to determine observed and expected numbers of people with subsequent primary cancers in each, based on person-years at risk, and calculated standardized risk ratios (RR). RESULTS: Comparing the NMSC cohort with the non-NMSC cohort, the RR for all subsequent malignant cancers combined was 1.36 [95% confidence interval (CI), 1.35-1.37]. Significantly increased RRs (P < 0.05) were found for 26 of the 29 cancer types studied, in particular for salivary gland, melanoma, bone, and upper gastrointestinal tract cancers. The RRs were also particularly high when comparing younger people with and without NMSC. CONCLUSIONS: NMSC is strongly associated with a broad spectrum of other primary cancers, particularly in younger age groups. The pattern suggests a genetic or early-acquired etiologic association. IMPACT: These results represent what can be done using very large, linked, routinely collected administrative datasets; but such datasets lack detail. Further work to establish the mechanisms behind these associations is warranted