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. All tests of statistical significance were two-sided.
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 statistically significant steady increase in the frequency, IR and SIR for second primary melanoma. For example, in the 1960s cohort, <1% (1.0 (95% CI = 0.5-1.7) and 1.1 (95% CI = 0.5-1.9) per 1,000 person-years in women and men, respectively) had second primary melanoma and this rose to 6.4% (7.5 (95% CI = 6.8-8.3) per 1,000 person-years) in the women and 7.9% (10.3 (95% CI = 9.3-11.2) 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. Further, in patients diagnosed with a second melanoma, the frequency of those having >2 melanomas increased statistically significantly and was 0.0% in the 1960s and rose to 18.0% in the 2000s (P <.001).
Conclusions
This is the first study to evaluate and report on a rising trend for subsequent primary melanoma. Additional primary melanomas worsen the patients’ survival and precautions are needed to turn this steep upgoing trend.
