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In a cohort of 6,146 patients with a first primary MCC, a total of 725 (11.8%) developed subsequent primary cancers. For solid tumors, the risk was highest for cutaneous melanoma and papillary thyroid carcinoma, while for hematologic cancers, the risk was increased for non-Hodgkin lymphoma.
“Our study does confirm that patients with MCC are at higher risk for developing other cancers,” study author Lisa C. Zaba, MD, PhD, associate professor of dermatology and director of the Merkel cell carcinoma multidisciplinary clinic, Stanford (Calif.) Cancer Center, said in an interview. “MCC is a highly malignant cancer with a 40% recurrence risk.”
Because of this high risk, Dr. Zaba noted that patients with MCC get frequent surveillance with both imaging studies (PET-CT and CT) as well as frequent visits in clinic with MCC experts. “Specifically, a patient with MCC is imaged and seen in clinic every 3-6 months for the first 3 years after diagnosis, and every 6-12 months thereafter for up to 5 years,” she said. “Interestingly, this high level of surveillance may be one reason that we find so many cancers in patients who have been diagnosed with MCC, compared to the general population.”
The study was published online in JAMA Dermatology.
With the death of “Margaritaville” singer Jimmy Buffett, who recently died of MCC 4 years after his diagnosis, this rare, aggressive skin cancer has been put in the spotlight. Survival has been increasing, primarily because of the advent of immunotherapy, and the authors note that it is therefore imperative to better understand the risk of subsequent primary tumors to inform screening and treatment recommendations.
In this cohort study, Dr. Zaba and colleagues identified 6,146 patients from 17 registries of the Surveillance, Epidemiology, and End Results (SEER) Program who had been diagnosed with a first primary cutaneous MCC between 2000 and 2018.
Endpoints were the ratio of observed to expected number of cases of subsequent cancer (Standardized incidence ratio, or SIR) and the excess risk.
Overall, there was an elevated risk of developing a subsequent primary cancer after being diagnosed with MCC (SIR, 1.28; excess risk, 57.25 per 10,000 person-years). This included the risk for all solid tumors including liver (SIR, 1.92; excess risk, 2.77 per 10,000 person-years), pancreas (SIR, 1.65; excess risk, 4.55 per 10,000 person-years), cutaneous melanoma (SIR, 2.36; excess risk, 15.27 per 10,000 person-years), and kidney (SIR, 1.64; excess risk, 3.83 per 10,000 person-years).
There was also a higher risk of developing papillary thyroid carcinoma (PTC) (SIR, 5.26; excess risk, 6.16 per 10,000 person-years).
The risk of developing hematological cancers after MCC was also increased, especially for non-Hodgkin lymphoma (SIR, 2.62; excess risk, 15.48 per 10,000 person-years) and myelodysplastic syndrome (SIR, 2.17; excess risk, 2.73 per 10,000 person-years).
The risk for developing subsequent tumors, including melanoma and non-Hodgkin lymphoma, remained significant for up to 10 years, while the risk for developing PTC and kidney cancers remained for up to 5 years.
“After 3-5 years, when a MCC patient’s risk of MCC recurrence drops below 2%, we do not currently have guidelines in place for additional cancer screening,” Dr. Zaba said. “Regarding patient education, patients with MCC are educated to let us know if they experience any symptoms of cancer between visits, including unintentional weight loss, night sweats, headaches that increasingly worsen, or growing lumps or bumps. These symptoms may occur in a multitude of cancers and not just MCC.”
Weighing in on the study, Jeffrey M. Farma, MD, interim chair, department of surgical oncology at Fox Chase Cancer Center, Philadelphia, noted that MCC is considered to be high risk because of its chances of recurring after surgical resection or spreading to lymph nodes or other areas of the body. “There are approximately 3,000 new cases of melanoma a year in the U.S., and it is 40 times rarer than melanoma,” he said. “Patients are usually diagnosed with Merkel cell carcinoma later in life, and the tumors have been associated with sun exposure and immunosuppression and have also been associated with the polyomavirus.”
That said, however, he emphasized that great strides have been made in treatment. “These tumors are very sensitive to radiation, and we generally treat earlier-stage MCC with a combination of surgery and radiation therapy,” said Dr. Farma. “More recently we have had a lot of success with the use of immunotherapy to treat more advanced MCC.”
Dr. Zaba reported receiving grants from the Kuni Foundation outside the submitted work. No other disclosures were reported. Author Eleni Linos, MD, DrPH, MPH, is supported by grant K24AR075060 from the National Institutes of Health. No other outside funding was reported. Dr. Farma had no disclosures.