Melanoma

Recurrence Rate of In Situ Melanoma Increasing

The long-term risk of recurrence is very similar in invasive and in situ melanoma, despite significant differences in recurrence rate in the first 2 years post-diagnosis.

In order to compare the recurrence risk associated with each form of melanoma, researchers collected data from patients with a first diagnosis of melanoma and no history of other types of cancer: 55,661 patients were classified as in situ, 97,614 were local invasive, and 14,999 were regional/distant invasive. The patients were part of the Surveillance, Epidemiology, and End Results program; all initial diagnosis data was collected 1973 and 2011, with a 5- or 10-year follow-up.
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In the in situ group, researchers observed an incidence rate of 4.2 per 1000 person-years. In comparison, the invasive group reported a 3.7 incidence rate and the regional group recorded a 4.7 incidence rate.

Researchers also measured recurrence rate by duration of time since diagnosis, finding higher rates of recurrence in the invasive group during the first 2 years of follow up. After 2 years, the recurrence rate leveled off across the 3 groups.

  • 2 months to 1 year: in situ HR 1.0, localized 1.31 (95% CI 1.11-1.54), regional/distant 1.75 (1.37-2.24)
  • 1 to 2 years: 1.0, 1.17 (0.99-1.39), 1.42 (1.07-1.89)
  • 2 to 5 years: 1.0, 1.07 (0.96-1.19), 1.21 (0.98-1.51)
  • 5 to 10 years: 1.0, 1.02 (0.92-1.14), 1.01 (0.79-1.29)

The study was presented at the annual meeting of the American Academy of Dermatology.

—Michael Potts

Pomerantz H. Risks of subsequent invasive melanoma after melanoma in situ compared to after invasive melanoma: A population-based study, 1973-2011. Presented at the AAD Summer Meeting 2014; Abstract 155. August 9, 2014.