Researchers at the University of Michigan Health System have found a new indicator that may predict which patients who have a common type of throat cancer most likely have the cancer in other parts of their bodies.

Patients with oropharyngeal squamous cell carcinoma who had "matted" lymph nodes, nodes that are connected, had a 69 percent survival rate over three years, compared to 94 percent for patients without matted nodes, according to a study published online in Head & Neck.

The oropharynx is the middle part of the throat which includes the back of the tongue, soft palate, and tonsils.

"The spread of cancer throughout the body accounts for about 45 percent of the deaths from oropharyngeal carcinoma," said the study's senior author, Douglas B. Chepeha, M.D., M.S.P.H., an associate professor of otolaryngology head and neck surgery at the U-M Medical School.

"Our findings may help doctors identify patients who are at higher risk for having their cancer metastasize and who would benefit from additional systemic therapy. Conversely, some patients without matted nodes may benefit from a reduction of the current standard treatment, which would cut down on uncomfortable side effects."

The findings indicated an increased risk of throat cancer in smokers who smoke tobacco and or marijuana, heavy alcohol use, and HPV infection.

Researchers also found that matted nodes appear to be an especially strong indicator of increased risk among patients who are HPV-positive.

But overall the patients with the best outcomes were HPV-positive nonsmokers.

"It's not clear why we're finding these survival differences for patients who have matted nodes," says study lead author Matthew E. Spector, M.D., a head and neck surgery resident at U-M who won a national award from the American Head and Neck Society for this work.

"It is possible that there are biological and molecular differences in these types of tumors, which can be explored in future research."

The researchers analyzed 78 cancer patients who were part of a clinical trial. The patients had stage III or IV squamous cell carcinoma of the oropharynx and had not had any previous treatment. Sixteen of the 78 patients had matted nodes.

"It's significant that we've identified this new marker that can help us predict which patients have worse survival odds," Chepeha said. "Now we need to go one step further and figure out what mechanisms are at work and how we can use this knowledge to improve survival rates."