Hip fracture history and risk of nonmelanoma skin cancer: a Danish population-based study

BACKGROUND Vitamin D deficiency is associated with osteoporotic fractures, such as hip fracture. Sun exposure, the natural source of vitamin D, is the main risk factor for basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). In this study, we examined the association between a history of hip fracture and risk of BCC and SCC. METHODS We conducted a population-based case-controlled study using data on BCC and SCC cases registered in the Danish Cancer Registry from 1990-2005. For each case, we selected five population controls matched by age and gender. We used conditional logistic regression to compute odds ratios (OR) and 95% confidence intervals (CI), while adjusting for chronic diseases and socioeconomic status. RESULTS A history of hip fracture was associated with a decreased risk of BCC (OR 0.90, 95% CI 0.85-0.94), which was most pronounced in cases of tumors on the trunk, extremities, or at multiple sites. We found no association for SCC (OR 1.07, 95% CI 0.98-1.17). CONCLUSION Our study showed an inverse association between history of hip fracture and risk of BCC, but not of SCC. Sun exposure, resulting in vitamin D synthesis, may explain the link between the two diseases.