RESUMO
Estimating the population attributable fraction (PAF) of melanomas due to sun exposure is challenging as there are no unexposed population nor reliable exposure data. In high incidence countries, a historic cohort of the South Thames cancer registry was used as a minimally exposed population using the formula PAF = (observed incidence-incidence in minimally exposure)/observed incidence. In this study, we apply this method, constructing a minimally exposed cohort for Colombia and also using the historical South Thames data, using melanoma incidence data from the population-based cancer registry of Cali, Colombia for the period 1967-2012. The historic cohort incidence rates were very similar to those of Thames, but cohort effects were smaller for women and nonexistent for men. Age-specific incidence rates of these minimally exposed cohorts were applied to recent population numbers. For females, PAFs were 19% using the historic Thames cohort and 25% using the historic Cali cohort, corresponding numbers for males were 62% (vs. Thames) and 0% (vs. Cali). Taking into account the incidence rates of acral melanomas, which are not sun related, the PAF increased in women to 26% (vs. Thames) and 34% (vs. Cali) and for men 77% (vs. Thames). This exercise shows the modest contribution of exposure to ultraviolet radiation in the burden of melanoma in low-incidence countries, as well as the importance to take into consideration the acral lentiginous melanomas.
