Risk of second primary malignancies following a diagnosis of cutaneous malignant melanoma or nonmelanoma skin cancer in Alberta, Canada from 1979 to 2009

Abstract

Recent studies have revealed geographical variations with respect to the risk of second primary malignancies (SPMs) following cutaneous malignant melanoma (CMM) and nonmelanoma skin cancer (NMSC). To provide the largest analysis of the risk of SPM following skin cancers in Canada and to detect associations that may shed light on common pathogeneses between linked malignancies. Relative risks for development of SPMs following a diagnosis of CMM or NMSC were calculated via a retrospective analysis of data retrieved from the Alberta Cancer Registry (ACR) from 1979 to 2009. From 1979 to 2009, 85,967 NMSC and 6884 CMM incident cases were recorded in the ACR. In total 19,869 SPMs were identified following a primary NMSC (7709 cutaneous and 12,160 noncutaneous), while 1437 SPMs (908 cutaneous and 529 noncutaneous) followed CMM. Patients with a previous history of skin cancer had a 60% increased risk of developing an SPM compared with those without [observed/expected ratio (O/E) 1.6, 95% confidence interval (CI) 1.6-1.7; P < 0.001]. Thirty and 10 different SPMs were significantly identified to follow a diagnosis of NMSC and CMM, respectively. Patients under the age of 40 years with a prior history of CMM had a marked increased expectancy for SPM [O/E 5.6, 95% CI 4.5-7.0; P < 0.001). Further studies are warranted to identify environmental and molecular connections among linked cutaneous and noncutaneous malignancies, which may lead to earlier detection of related neoplasms via expanded screening protocols and development of shared treatment regimens. Heightened surveillance for the development of SPMs in patients with CMM under the age of 40 years should be considered.