According to a new study at the University of Washington School of Medicine, patients treated for Merkel cell carcinoma (MCC) face a 5-year recurrence rate of 40 per cent. This is significantly higher than the recurrence rate of melanoma and other skin cancers. The findings of the research were published in the journal ‘JAMA Dermatology’. (Also read: Breast cancer during pregnancy can be aggressive; watch out for these symptoms)
Additionally, in the study cohort of more than 600 patients, 95 per cent of MCC recurrences happened in the first three years, suggesting that surveillance efforts should be focused on that span the authors wrote.
“Merkel cell carcinoma is a life-changing diagnosis. It can be time-consuming, costly and exhausting to undergo clinic visits, imaging studies and blood draws. Now we have data on the time intervals and cancer stages that merit higher or lower surveillance intensity,” said Dr Aubriana McEvoy, who led the research while she was at the University of Washington School of Medicine. She is currently a dermatology resident at Washington University in St. Louis.
Merkel cell cancer is rare, aggressive skin cancer, more often fatal than invasive melanoma and basal-cell and squamous-cell carcinomas. Merkel cell carcinoma is composed of cells that look very similar to ‘Merkel’ cells that are a key part of the epidermis, the skin’s outer layer. Normal Merkel cells communicate touch-related information such as pressure and texture to the brain.
This study comprised 618 patients (37 per cent female) whose ages ranged from 11 to 98 and whose median age was 69. In this cohort, initial treatment (surgery, radiation and systemic therapy) had a median duration of 90 days.
The authors sought to characterize the post-treatment recurrence risk of MCC diagnosed at pathologic (listed below) and clinical stages.
The risk of recurrence at one year was found to be:
11 per cent among patients diagnosed with stage I disease33 per cent among patients diagnosed with stages IIA/IIB disease30 per cent among patients diagnosed with stages IIIA disease45 per cent among patients diagnosed with stage IIIB disease58 per cent among patients diagnosed with stage IV disease
The investigators found four factors associated with higher recurrence risk: advanced age, male sex, immunosuppression, and a known primary lesion amid clinically detectable nodal disease.
As expected, survival among cohort patients was strongly dependent on cancer stage at the time of diagnosis: The MCC-specific survival rate at five years post-treatment was 95 per cent for patients diagnosed at stage I vs. 41 per cent for patients diagnosed at stage IV.
MCC survival “is a more accurate measure of disease risk than overall survival,” the authors wrote, because patients, with a median age of 70 at diagnosis, are at “considerable” risk of death from conditions unrelated to cancer.
Again, stage at diagnosis was associated with a meaningful difference: 90 per cent of deaths among patients with stage IV disease were attributed to MCC, whereas just 57 per cent of deaths among patients diagnosed at stage I were attributed to the disease.
“This is tricky cancer to beat because it comes back — after optimal therapy in almost half of the patients. We want to help patients figure out how much remaining risk of recurrence they have at various times after diagnosis,” said Dr Paul Nghiem, chair of dermatology at the UW School of Medicine. He is the study’s senior author and an expert on Merkel cell cancer.
He added that the UW’s database is likely the most comprehensive anywhere for MCC case therapies and outcomes.
“These are all patients who were followed meticulously to know why they’re doing well or not doing well. The size of the data set has allowed us to see patterns more clearly, and we need data to drive optimal decision-making,” Nghiem said.
U.S. incidence of MCC is low relative to other skin cancers, but also is on a steep upward trajectory because the disease is closely associated with age. About 3,200 cases will be diagnosed this year, according to a 2018 study by Nghiem and colleagues.
By contrast, about 100,000 new melanomas will be diagnosed this year. Basal cell carcinoma is far more common, with 3.6 million cases diagnosed annually, and squamous cell carcinoma numbers 1.8 million new cases a year, according to the Skin Cancer Foundation.
Each of these cancers has a significantly lower post-treatment recurrence rate than MCC, the authors noted: melanoma at 19 per cent, squamous cell at 5-9 per cent, basal cell at 1-2 per cent.