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Lentigo maligna incidence significantly increased in defined population

There was a significant increase in the incidence of lentigo maligna in a specific Minnesota population of adults during more than three decades, according to epidemiologic study results.

Jerry D. Brewer, MD, dermatologist, Mayo Clinic, Rochester, Minn., and colleagues identified all adult residents of Olmsted County, Minn., with a lifetime diagnosis of lentigo maligna (LM) between 1970 and 2007 by searching databases in the Rochester Epidemiology Project. One hundred forty-five patients (median age at diagnosis, 70 years; 64% men) were included in the study. Demographic, clinical and surgical data were determined through medical record reviews.

 

Jerry D. Brewer

Patient treatment changed during the course of the study period, including the availability of Mohs micrographic surgery after 1986 in the study region.

There was a significant increase of LM incidence with age (P<.001) and by year of diagnosis (P<.001), with incidence higher for men than women (P<.001). Forty-two patient deaths were reported at final follow-up; however, none died of LM. Five patients had a local recurrence at 0.4, 2.8, 4.5, 9.2 and 13.3 years after diagnosis, respectively.

“Estimated local recurrence-free survival at 5, 10, 15 and 20 years after diagnosis was 98%, 96%, 92% and 92%, respectively,” the researchers reported.

Adults had an overall age- and sex-adjusted LM incidence of 6.3 per 100,000 person-years, with an increase of 2.2 per 100,000 person years in 1970 to 1989 and 13.7 per 100,000 person years in 2004 to 2007.

“This study demonstrates a significant increase in the incidence of LM among residents of Olmstead County, Minn., over an extended time frame,” the researchers concluded. “The treatment of LM in this population was very effective, with a 100% disease-specific survival. The increasing incidence of [LM] suggests that treatment of these cancers will add an increased burden on dermatologic clinical practice and will increase the cost of care.”

Disclosure: The researchers report no relevant financial disclosures.