In situ melanoma high risk for subsequent diagnosis

Source: Family Practice News Digital Network, March 2014, by DENISE NAPOLI

In situ melanoma patients have a significant, substantially elevated risk for subsequent invasive or in situ melanoma – nearly as high as the risk for patients presenting with more invasive disease.

The finding means that “education and continued surveillance are paramount not only for persons with an invasive melanoma but also for persons with an in situ melanoma," wrote Danny R. Youlden in JAMA Dermatology, published online March 19 (doi:10.1001/jamadermatol.2013.9852).

Mr. Youlden, a biostatistician with Cancer Council Queensland, in Brisbane, Australia, and his colleagues looked at 39,668 cases of first primary invasive melanoma, and 22,845 patients with first primary in situ melanoma, diagnosed between 1982 and 2005.

Patients were followed for a median of more than 9 years, during which time there were 5,358 subsequent primary invasive melanomas; 3,520 (66%) of these occurred in patients with previous invasive melanomas.

Compared with the general Australia population, that amounted to a standardized incidence ratio for primary invasive melanoma of 5.42 for patients with previous invasive melanoma diagnoses (95% CI, 5.23-5.61) and 4.59 for patients with previous in situ melanoma (95% CI, 4.37-4.82).

Moreover, the authors found that the body site of the second melanoma was typically the same as for the first invasive or in situ diagnosis, especially on the head and lower extremities; in particular, females with a first primary invasive melanoma on the head had a standardized incidence ratio of 13.32 for a second primary invasive melanoma of the head, compared with the general population (95% CI, 10.28-16.98).

The authors disclosed no conflicts of interest; several reported grants from the National Health and Medical Research Council.