Patients with primary invasive melanoma at increased risk for subsequent invasive melanoma

Source: Healio.com, May 2014

Patients with a primary invasive or in situ melanoma had a significantly increased relative risk for developing a subsequent invasive melanoma, according to recent study results.

Danny R. Youlden, BSc, and fellow researchers used population-based data for melanoma diagnoses collected by the Queensland Cancer Registry in Australia to conduct a retrospective cohort study. All Queensland residents aged 15 years and older diagnosed with a first primary invasive or in situ melanoma between 1982 and 2005 were included. There were 39,668 cases of first primary invasive melanoma (55.8% male) and 22,845 cases of first primary in situ melanoma (54.4% male) identified through 2010.
Danny Youlden

“Standardized incidence ratios (SIRs) … were calculated by dividing the observed number of subsequent primary invasive melanomas by the product of the strata-specific incidence rates that occurred in the general population and the cumulative time at risk for the cohort,” the study said.

Researchers included 5,358 subsequent primary invasive melanomas diagnosed in 4,733 patients, determining incidence for patients with first primary invasive melanoma (SIR=5.42; 95% CI, 5.23-5.61) and those with in situ melanoma (SIR=4.59; 95% CI, 4.37-4.82). Throughout follow-up, SIRs remained elevated.

Subsequent primary invasive melanomas usually occurred at the same site as the initial invasive or in situ melanoma, the researchers said. Females who had a first primary invasive melanoma on the head followed by a subsequent primary invasive melanoma there experienced the largest relative risk (SIR=13.32; 95% CI, 10.28-16.98).

“To our knowledge, we have quantified for the first time the relative risks by body site of a subsequent primary invasive melanoma being diagnosed in people with a first primary invasive or in situ melanoma,” the researchers concluded. “The relative risks were generally highest for the same body site, although the variation observed by key patient and tumor characteristics emphasizes that certain combinations of sites and demographic attributes require more vigilant follow-up.”