Blood Test Predicts Survival in Merkel Cell Carcinoma

A routine blood test may help predict survival in patients with an aggressive form of skin cancer known as Merkel cell carcinoma. This carcinoma is a rare type of skin cancer, usually striking older people and those with weakened immune systems.

Findings of investigators were presented on October 31, 2012, at the American Society for Radiation Oncology's 54th Annual Meeting, held in Boston (USA). Investigators at Fox Chase Cancer Center (Philadelphia, PA, USA) found that the total numbers of lymphocytes were directly proportional to outcomes in patients with Merkel cell carcinoma.

Matthew Johnson, MD, a resident physician in the department of radiation oncology at Fox Chase, and his colleagues found that patients with Merkel cell carcinoma with low numbers of the lymphocytes that participate in immune function did not live as long after treatment than those with higher lymphocyte counts did.

The team reviewed medical records of 64 patients treated for Merkel cell carcinoma between 1992 and 2010 at Fox Chase. All patients had their blood analyzed a month before surgery, chemotherapy, or radiation.

Approximately two-thirds of patients had normal absolute leukocyte counts (ALC). Along with longer overall survival, these patients were much more likely to be disease-free 60 months later (67%) than those with a low ALC (24%) were. ALC may be associated with survival because it is a marker of overall immune health, said Dr. Johnson, and healthier immune systems may keep a cancer in check.

"Since ALC has been tied to prognosis in other types of cancer, we were expecting to see some difference between patients with high and low counts," said Dr. Johnson. "But it was definitely a bigger difference than what we were anticipating."

Doctors routinely check a patient's ALC as part of a standard blood count, said Dr. Johnson. They just typically do not know how to interpret those particular results. Since checking a patient's ALC is already routine, it would be "reasonable, based on our conclusions," for a patient to ask his or her doctor for the results of that test, Dr. Johnson noted.

If a patient's ALC is particularly low, there is little the doctor would do differently to treat Merkel cell carcinoma, because such an aggressive cancer is always treated aggressively. But many patients believe it's helpful to know their prognosis, said Dr. Johnson. "ALC provides patients with some information about how long they may have left. There are a lot of patients who just want to know."

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Fox Chase Cancer Center