Abstract 1148P
Background
Over the past decades many regions have experienced a steady increase in the incidence of cutaneous melanoma. Here, we report on incidence trends for subsequent primary melanoma.
Methods
In this nationwide population-based study, patients diagnosed with a first primary cutaneous melanoma reported to the Swedish Cancer Registry, were followed for up to ten years for a diagnosis of subsequent primary melanoma. Patients were grouped with patients diagnosed with first melanoma in the same decade (1960s, 1970s, 1980s, 1990s and 2000s, respectively). Frequencies, incidence rates (IRs), standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) for second melanomas were calculated.
Results
54,884 patients with melanoma were included and 2,469 were diagnosed, within ten years, with subsequent melanomas. Over the five decades there was a significant steady increase in the frequency, IR and SIR for second primary melanoma. E.g., in the 1960s cohort, <1% (1,0 per 1,000 person-years) had second primary melanoma and this rose to 6.4% (7.5 per 1,000 person-years) in the women and 7.9% (10.3 per 1,000 person-years) in the men in the 2000s cohort. This rise was seen, independent of age, sex, invasiveness or site of the melanoma. The SIR for second melanomas was 14.2 (95% CI 9.1-22.6) in women and 16.5 (95% CI 8.4-29.5) in men the 1960s and the SIR rose to 23.8 (95% CI 21.8-25.9) in women and 27.4 (95% CI 24.4-30.0) in men in the 2000s. Further, in patients diagnosed with a second melanoma, the frequency of those diagnosed with three or more melanomas increased significantly, from 0% in the 1960s to 18% in the 2000s.
Conclusions
This is the first study to evaluate and report on a rising trend for subsequent primary melanoma. The increase for second primary melanomas has occurred in parallel to the incidence increase for melanoma in the overall population, however the rise for second primaries has been steeper. Changes in sun exposure habits in the general population have likely caused individuals with constitutional vulnerability traits to become more inclined to develop multiple primary melanomas. Additional primary melanomas worsen the patients’ survival and precautions are needed to turn this steep upgoing trend.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Hildur Helgadottir.
Funding
Grants from the Swedish Cancer Society (grant number CAN 2017/503) and The Cancer Research Funds of Radiumhemmet (grant number 194092).
Disclosure
All authors have declared no conflicts of interest.