People diagnosed with systemic mastocytosis (SM) face a significantly higher risk of developing skin cancers, especially malignant melanoma, according to a new large-scale study published recently in the Journal of the American Academy of Dermatology.
“[O]ur findings provide evidence that mastocytosis patients are at an increased risk of skin cancer, warranting heightened dermatologic surveillance, patient education on UV protection and avoidance of UV-based therapies,” explained this study’s authors.
Researchers found that these patients, compared to matched controls, had a 2.49 times higher lifetime risk of melanoma, along with elevated risks for squamous cell carcinoma and basal cell carcinoma. These results underscore the need for early skin surveillance and stronger guidance on UV protection in individuals living with SM.
Mastocytosis, which includes SM, is a disorder marked by the abnormal buildup and activation of mast cells, often causing allergic reactions, itching and other chronic symptoms. In systemic cases, these mast cells infiltrate organs beyond the skin. This new analysis used real-world health data from more than 69 U.S. health care organizations and included 20,119 patients with SM matched 1:1 with controls based on age, sex and relevant family history.
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Risk for skin cancer was highest in the first year after diagnosis. The hazard ratio for melanoma during that period reached 3.54, suggesting a more than threefold increase in risk compared to individuals without mastocytosis. Risks for squamous cell carcinoma and basal cell carcinoma also rose, though to a lesser extent. Importantly, elevated risk for melanoma and squamous cell carcinoma remained statistically significant even after accounting for early detection bias by excluding the first 30 days post-diagnosis.
Scientists believe the link between SM and skin cancer may stem from shared mutations, such as in the KIT gene, and from inflammatory substances released by mast cells that can damage skin cells or encourage abnormal growth. Chronic inflammation and high levels of S-tryptase, a marker of mast cell activity, may also contribute to the development of cancer. Some patients with mastocytosis receive UV therapy to relieve symptoms, which could further increase risk for skin cancer.
This study, the largest of its kind, provides strong evidence supporting a direct association between mastocytosis and skin cancers, particularly melanoma. While some limitations exist, such as missing data on sun exposure, the results highlight the importance of regular dermatologic exams and careful management of sun exposure in patients with SM.
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