Scientists say a simple blood test can help predict survival in patients with an aggressive form of skin cancer known as Merkel cell carcinoma.
Fox Chase Cancer Center researchers found that Merkel patients who had low levels of a particular type of immune system white blood cell — known as a lymphocyte — didn't live as long after treatment as those with higher counts.
The findings, presented at a meeting of the American Society for Radiation Oncology, suggest doctors could use a routine blood test to gauge a patient’s prognosis.
"With such a fast-growing cancer, we get one question a lot: 'How long do I have?' " said lead researcher Dr. Matthew Johnson, a resident physician in the Department of Radiation Oncology at Fox Chase. "That's usually hard to answer. These findings enable us to give a more educated response."
For the study, Johnson and his team reviewed medical records of 64 cancer patients between 1992 and 2010. All patients had had their blood analyzed the month before surgery, chemotherapy, or radiation.
The results showed half of the patients with white blood cell counts below a certain cutoff — 1,500 lymphocytes cells per cubic millimeter of blood — didn’t survive much more than two years after surgery, chemotherapy, or radiation. Half of those with normal levels lived eight years or more. And patients with higher levels lived even longer.
"Since [white cell levels have] been tied to prognosis in other types of cancer, we were expecting to see some difference between patients with high and low counts," said Johnson. "But it was definitely a bigger difference than what we were anticipating."
Merkel cell carcinoma is a rare and aggressive form of skin cancer, usually striking older people and those with weakened immune systems.