Prior nonmelanoma skin cancer linked to fewer fractures in old age

Older adults with a history of nonmelanoma skin cancer (NMSC) appear to have fewer incident fractures, according to a study.

Modifiable fracture risk factors related to an outdoor lifestyle such as more vitamin D sufficiency, greater bone mineral density (BMD), and improved bone microarchitecture seem to be responsible for the protective benefit of prior NMSC.

This prospective cohort analysis, with baseline and 10-year follow-up assessments, included 1,099 community-dwelling older adults aged 50–80 years. Histopathologically confirmed NMSC diagnosis was confirmed through a linkage with the Tasmanian Cancer Registry.

The investigators measured BMD and vertebral deformity by DXA, 25-hydroxyvitamin D (25[OD]D) by radioimmunoassay, bone microarchitecture by high-resolution peripheral quantitative computed tomography, melanin density by spectrophotometry, and skin photosensitivity and clinical fracture by questionnaire. Vitamin D deficiency was defined by 25(OH)D level <50 nmol/L.

Older adults with an NMSC reported prior to baseline had a reduced risk of incident vertebral deformity over 10 years (risk ratio [RR], 0.74; p=0.036). Similar reductions were noted for other types of fracture, but these were not statistically significant.

Prior NMSC significantly correlated with baseline (RR, 1.23; p=0.005) and 10-year longitudinal (RR, 5.9; p=0.014) vitamin D sufficiency and greater total body BMD (β, 0.021g/cm²; p=0.034), but not falls risk or muscle strength. 

Additionally, the association between prior NMSC and bone microarchitecture was age-dependent (p<0.05) for interaction). Prior NMSC in the oldest age tertile correlated with greater volumetric BMD (β, 57.8–62.6; p=0.002 to 0.02) and less porosity (β, –4.6 to –5.2; p=0.002 to 0.009) at cortical, compact cortical, and outer transitional zones.

“Prior NMSC, a biomarker of cumulative lifetime sun exposure, is associated with reduced fracture risk later in life," the investigators said.