A routine blood test may help predict survival in patients with an aggressive form of skin cancer known as Merkel cell carcinoma, according to new findings by Fox Chase Cancer Center researchers. The results will be presented on Wednesday, October 31 at the American Society for Radiation Oncology's 54th Annual Meeting.
"With such a fast-growing cancer, we get one question a lot: 'how long do I have?'," says Matthew Johnson, MD, a resident physician in the Department of Radiation Oncology at Fox Chase and lead author on the study. "That's usually hard to answer. These findings enable us to give a more educated response."
Specifically, Johnson and his colleagues found that patients with Merkel cell carcinoma who had low numbers of lymphocytes-a type of white blood cell that participates in immune function-didn't live as long after treatment as those with higher lymphocyte counts.
The difference was remarkable. Among people whose absolute lymphocyte count (ALC) was below the cutoff (1500 cells per cubic millimeter of blood, or 1.5 k/mm3), half survived 25 months or less after surgery, chemotherapy, or radiation. Among those with ALCs in the normal range, half lived close to 100 months or more following treatment. Disease-free survival was also much longer in patients with higher ALCs.
"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," says Johnson. "But it was definitely a bigger difference than what we were anticipating."
Merkel cell carcinoma is a rare and aggressive type of skin cancer, usually striking older people and those with weakened immune systems.
During the study, Johnson and his team reviewed medical records of 64 patients treated for Merkel cell carcinoma between 1992 and 2010 at Fox Chase. All patients had had their blood analyzed the month before surgery, chemotherapy, or radiation.