Patients with in situ melanoma at higher risk for subsequent melanoma after 2 years

Source: Healio.com/Dermatology March 2015

Patients whose first cancer was melanoma in situ had a greater risk of developing subsequent melanoma after 2 years following the first diagnosis compared with patients whose first cancer was invasive melanoma, according to recently published study results.

Researchers identified 55,551 patients with melanoma in situ as their first primary cancer and 112,613 patients with invasive melanoma as first primary cancer using data from the national Surveillance, Epidemiology and End Results (SEER) program from 1973 to 2011. Median follow-up after patients’ first diagnosis was 7 years for the melanoma in situ group and 8.5 years in the invasive melanoma group.

The risk of in situ or invasive melanoma at any stage within 2 years after first melanoma was not different between the two cohorts (HR = 1.02; 95% CI, 0.95-1.10). However, the invasive melanoma cohort had a higher risk of subsequent invasive melanoma compared with the melanoma in situ cohort during the first 2 years (HR = 1.36; 95% CI, 1.21-1.51), according to the researchers. After 2 years, patients in the invasive melanoma group were less likely to develop subsequent melanoma than patients in the melanoma in situ group (2-10 years: HR = 0.84; 95% CI, 0.79-0.88; after 10 years: HR = 0.78; 95% CI, 0.71-0.85).

The melanoma in situ cohort was more likely to develop subsequent melanoma of any stage after 2 years when compared with the patients with initial invasive melanoma (P< .001). Additionally, subsequent invasive melanoma after 10 years (HR = 0.84; 95% CI, 0.79-0.94) and subsequent melanoma in situ at all the time points (P< .001) also were more likely to occur in the melanoma in situ cohort compared with the invasive melanoma cohort, the researchers reported.

The researchers concluded patients with a melanoma in situ diagnosis may benefit from long-term surveillance for subsequent melanomas.