Updates in staging, management may benefit future of Merkel cell carcinoma treatment

Issue: April 25, 2016

NEW YORK — Updates to the staging system and management guidelines for Merkel cell carcinoma may help clinicians in the appropriate treatment of this rare disease, according to a speaker at HemOnc Today Melanoma and Cutaneous Malignancies.

Merkel cell carcinoma is extremely rare, with only approximately 1,600 new cases each year in the United States, Manisha Thakuria, MD, director of the Merkel Cell Carcinoma Clinic in the Center for Cutaneous Oncology at Dana-Farber/Brigham & Women’s Cancer Center and instructor in the department of dermatology at Harvard Medical School, said during her presentation.

Manisha Thakuria

The disease tends to be more aggressive than melanoma — in part because most patients present at a late stage — with a one in three case fatality rate, compared with one in seven case fatality rate for melanoma.

“This is also a relatively new entity, with the first case described in 1978,” Thakuria said. “There have only been a few decades in which data were collected.”

Key management challenges include frequently delayed diagnosis in these patients due to the cancer’s indistinct clinical appearance. Moreover, the optimal care of patients is debated.

“The data is very limited with this cancer, we don’t have randomized controlled trials yet,” Thakuria said. “Our treatment guidelines are very broad, which makes it hard for the individual clinician, because a lot of our decisions are guided by experience with this disease.”

Further, multiple staging systems have been published in the literature, and the first consensus American Joint Committee on Cancer (AJCC) staging system for Merkel cell carcinoma was not published until 2009.

“The literature is very muddled because there were several different staging systems originally,” Thakuria said. “Some were three-stage systems and others were four-stage systems. You can imagine the confusion this causes when you look back at the literature when referring to a patient with stage III disease, and you don’t know if it’s referring to regional disease or metastatic disease.”

The new AJCC 8th edition staging system — not yet published — will feature a division of clinical and pathological characteristics, and is expected later this year, Thakuria said. This system will look more like that used in melanoma, although the specific details have not yet been released.

National Comprehensive Cancer Network guidelines also have been updated this year. One key update includes the recommendation to consider irradiating the nodal basins of head and neck sites in appropriate patients who do not undergo or fail sentinel lymph node biopsy.

“There is a higher risk of false negatives in the head and neck, because there is aberrant draining, and often more than one nodal basin that it will drain to,” Thakuria said.

The principles of radiation were extensively revised in the new guideline. Further, the guidelines continue to emphasize the importance of sentinel lymph node biopsy with new specific details to help guide clinicians.

“This is helpful, because I have seen cases coming in from the community, where providers understood that the patient needed to have a sentinel lymph node biopsy, but it wasn’t performed in the correct order, and then the patient suffered because of that,” Thakuria said.

The updated guidelines also include a special section on immunosuppressed patients, who are at high risk for recurrence. These patients should undergo more frequent follow-up, and use of iatrogenic immunosuppression should be decreased whenever possible, Thakuria said. – by Alexandra Todak

Reference:

Thakuria M. What’s new in Merkel cell carcinoma? Presented at: HemOnc Today Melanoma and Cutaneous Malignancies; March 18-19, 2016; New York.

Disclosure: Thakuria reports no relevant financial disclosures.