NEW YORK (Reuters Health) - What makes a difference in Merkel cell carcinoma? Providing guideline-based treatment, according to a new review of more than 4,000 cases.
Dr. John T. Vetto and colleagues from Oregon Health & Science University in Portland found that complete lymph node dissection was associated with improved disease-specific survival in patients with positive sentinel lymph node biopsy (SLNB).
In clinically node-negative patients who have a positive SLNB, radiation and chemotherapy does not appear to affect survival, they report online July 30 in The American Journal of Surgery.
"This is retrospective evidence suggesting that we don't need radiation for a negative sentinel node. In my practice, I see radiation therapists hesitant to radiate negative nodes and doing it less and less. So here is some data to say that's okay," Dr. Vetto noted in an interview with Reuters Health.
"Merkel cell carcinoma (MCC) is a very aggressive cancer," Dr. Katia T. Papalezova, a surgical oncologist at Montefiore Einstein Center for Cancer Care in New York City, who wasn't involved in the study, told Reuters Health by email.
The findings of this review largely "support the current National Comprehensive Cancer Network guidelines," she said. "At Montefiore Einstein Center for Cancer Care, we also recommend that all patients are evaluated by a multidisciplinary tumor board when a diagnosis is made."
MCC is a primary neuroendocrine cancer of the skin, originally termed trabecular carcinoma. MCC "is not the rare disease that it was once thought to be," Dr. Vetto said. The data suggest that the incidence is "increasing," which is not surprising because it's related to sun exposure, immunosuppression and aging, which are also becoming more common, he explained.
Typically patients present with rapidly growing, firm, non-tender, painless and sometimes ulcerated skin nodules which are red or bluish in color, may be up to several centimeters in size, and appear predominantly on sun-exposed skin.
Current treatment recommendations advise surgical excision of the primary tumor with wide margins (1 to 3 cm) followed by SLNB or elective lymphadenectomy (for clinically node-negative cases) because 25% to 30% of patients have regional nodal disease at diagnosis.
Knowledge of MCC is largely based on single-center retrospective analyses of small series. By pooling data from state cancer registries in California, Oregon and Washington, Dr. Vetto and colleagues had cohort of 4,038 MCC patients to evaluate prognostic factors and treatment outcomes.
The cohort had a mean age at diagnosis of 73 years, 61% were male and 88% were white.
Male gender, age older than 60, and tumor size larger than 21 mm were all associated with lower disease-specific survival (p=0.0001), the authors report. These findings are in line with a previous study by Tarantola et al. and suggest "possible future refinements to the AJCC staging criteria for T stage, which currently only includes size," they say.
They found that patients with positive nodes or no documented nodal evaluation had worse five-year disease-specific survival relative to node-negative patients (p=0.0001).
A lack of nodal evaluation was associated with significantly lower disease-specific survival compared with lymph node evaluation by SLNB (hazard ratio, 1.72). Of the 1,140 patients who underwent SLNB, 567 patients had complete lymph node dissection for positive findings.
Complete lymph node dissection was associated with improved disease-specific survival in patients with a positive SLNB (p=0.0001).
In clinically node-negative patients with positive SLNB, disease-specific survival was not affected by radiation (p=0.16) or chemotherapy.
"A previously unaddressed question was whether RT was beneficial in those patients specifically known to be node-negative. Our study found that there was no statistical survival advantage to giving adjuvant RT to patients with a negative SLNB. Presumably the risk of nodal failure in our SLN negative patients was low enough to obviate the need for radiation therapy," the authors note in their article.
The study had its share of limitations, the authors say, including the "inherent downsides associated with the use of the state tumor registry databases, such as an unknown incidence of disease-specific recurrence."
Also, they only had data on SLN biopsy after 2004 and they didn't have information on patient comorbidities such as immunosuppression, which can influence individual outcomes. Also, the study doesn't address "potential newly targeted therapies for MCC aimed at the Merkel cell polyomavirus (MCV) or other monoclonal antibody targets."
Dr. Vetto thinks the findings "call for a clinical trial, and there are enough patients out there that you can do a trial."
Dr. Papalezova told Reuters Health, "Prospective randomized clinical trials are needed to evaluate treatment outcomes and prolonged patient survival, as retrospective studies can have inherent difficulties. We need to encourage patients to participate in clinical trials so this can be achieved."
SOURCE: http://bit.ly/1shspBz
Am J Surg 2014.
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