A new analysis in non-Hispanic whites suggests that rising melanoma rates are real, not attributable to increased levels of detection, and that the burden of the disease could rise significantly in the coming years.
The incidence of melanoma in light-skinned individuals has been rising worldwide in recent years, but it remains unclear whether that trend is due to an increase in the disease, or better screening and diagnosis. The new results are drawn from California, and track incidence and stage at diagnosis of melanoma across different socioeconomic status (SES) groups. Across all groups, the researchers found increases not only in incidence, but also in advanced disease.
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“Our findings support a true real rise in incidence of melanoma across all thicknesses and stages, and not just thinner, more indolent tumors that may be due to increased screening or diagnosis,” lead researcher Susan Swetter, MD, said in an interview. The study was published online in the Journal of Investigative Dermatology (J Invest Dermatol. 2017 Jul 20. pii: S0022-202X(17)31867-5. doi: 10.1016/j.jid.2017.06.024).
Dr. Susan Swetter
Overall, the incidence rose 25% in men from 1998-2002 to 2008-2012 (an average annual age-adjusted incidence of 34.7 to 43.5 per 100,000 person-years), and by 21% in women between those two time periods (from 21.7 to 26.2 per 100,000). Melanoma incidence rate ratios (IRR) increased across all SES classes: by 27% among men in the highest SES neighborhoods, and by 12% among men in the lowest SES neighborhoods. For women, the rates increased by 28% and 13% respectively.
The highest increases in the incidence of regional and distant disease occurred in the lowest SES neighborhoods, nearly doubling in men (distant disease IRR, 1.87; 95% CI, 1.39-2.53; regional disease IRR, 1.93; 95% CI, 1.51-2.47). Women in these neighborhoods also experienced a significant increase in regional disease (IRR, 1.44; 95% CI, 1.00-2.08), but not distant disease.
Incidence of diagnosis with the thickest tumors (greater than 4 mm) rose significantly in most neighborhood SES quartiles, with the exception of the men in the lowest SES quartiles, who had a lower increase that was of borderline significance.
The results solidify the evidence that melanoma incidence is truly increasing, but they also have public health implications. The rising incidence of more advanced disease suggests a heightening health care burden from melanoma in the coming years, but also points to strategies for prevention, according to Dr. Swetter. “It’s important that we focus not only on primary prevention. We need methods to enhance early detection, especially in areas where there is lower access to dermatologists and even primary care providers, who can assist in this effort,” she said.
The Stanford Cancer Institute funded the study. Dr. Swetter reported having no financial disclosures.