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Merkel cell cancers recur more often than other skin cancers, usually within three years

JAMA Dermatology
Reuters Health - 03/03/2022 - Merkel cell carcinoma (MCC) recurs much more often than other skin cancers, and most recurrences are within three years of a diagnosis, researchers say.

MCC stage seems to be prognostic, and can be used to inform surveillance intensity.

"We spent years being frustrated by our inability to accurately tell patients what the risk is that their MCC will come back," Dr. Paul Nghiem of the University of Washington in Seattle told Reuters Health by email. "Because recurrences do not always lead to death, and sometimes a recurrence precedes death by many years, it was hard to know what to tell patients besides general concepts like 'risk goes up with cancer stage', and 'risk falls after years of no recurrence.'"

"It was reassuring to see that our larger cohort had a 40% recurrence risk, in the middle of prior reports of 27%-77%," he said. "Surprisingly, when we split our population into three groups based on the year patients were diagnosed, the three independent groups had essentially the same rate of recurrence (39.5%, 39.2%, and 40.4%). This recurrence rate is far higher than that of other more common types of skin cancer."

"Another important difference from other skin cancers is how quickly a patient's risk of MCC recurrence falls after diagnosis," he added. "With over 90% of recurrences arising in the first three years, rapid de-escalation of follow-up scans, blood tests, and visits is appropriate."

As reported in JAMA Dermatology, Dr. Nghiem and colleagues analyzed data on 618 MCC patients (median age, 69; 37%, women) enrolled in a Seattle-based data repository between 2003 and 2019. Among them, 223 experienced a recurrence of MCC.

The median follow-up among living patients was 4.3 years. Overall, the 5-year recurrence rate was 40%.

Risk of recurrence in the first year was 11% for patients with pathologic stage I; 33% for pathologic stage IIA/IIB; 30% for stage IIIA; 45% for stage IIIB; and 58% for stage IV, with 95% of recurrences occurring within the first three years.

Beyond stage, four factors were associated with increased recurrence risk: immunosuppression (hazard ratio, 2.4); male sex (HR, 1.9); known primary lesion among patients with clinically detectable nodal disease (HR, 2.3); and older age (HR, 1.1).

Among 187 deaths in the cohort, 121 (65%) were due to MCC. The MCC-specific survival rate was strongly stage-dependent - i.e., 95% at 5 years for patients with pathologic stage I versus 41% for pathologic stage IV.

Among patients presenting with stage I to II MCC, a local recurrence arising within/adjacent to the primary tumor scar did not appreciably diminish survival compared with patients who had no recurrence (85% vs. 88% MCC-specific survival at 5 years).

"Stage- and time-specific recurrence data can assist in appropriately focusing surveillance resources on patients and time intervals in which recurrence risk is highest," the researchers conclude.

They have combined their stage data and other known risk factors (immune suppression, sex, age) into a web app that calculates a patient's recurrence risk based on the interval since initial treatment. When the risk falls below 2%, Dr. Nghiem said, "we can 'graduate' them from surveillance."

The beta version of the app is available at: www.merkelcell.org/recur.

UC Health oncologist Dr. Rekha Chaudhary of the UC College of Medicine in Ohio, commented in an email to Reuters Health. "Previously, detecting (MCC) recurrence early was of limited utility because we didn't have good treatments for recurrent disease. Now we have immunotherapy that has significant efficacy against MCC. Therefore...it is important to detect a recurrence earlier."

"This study was very helpful in predicting those rates of recurrence," she said. "Following an MCC patient who has had a complete resection closely is very important now, given the new innovative treatments, and national guidelines should be adjusted accordingly. These guidelines should especially address the first three years after diagnosis and patients that have lymph node-positive disease, given their higher risk of recurrence."

SOURCE: https://bit.ly/3MlbURu JAMA Dermatology, online February 23, 2022.

By Marilynn Larkin

© 2023 The Author(s). Published by Medicom Medical Publishers.
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