By Jocelyn Selim
An Unexpected Disparity
HPV plays a surprising role in racial disparities among head and neck cancer survivors
By Jocelyn Selim
For survivors of oropharyngeal cancer—a cancer that begins at the base of the tongue and tonsils—it makes a difference if you’re black or white.
Researchers have long known that blacks have a lower chance of surviving specific kinds of cancer than whites. The Black/White Cancer Survival Study, launched in the 1980s by the National Cancer Institute’s Surveillance, Epidemiology and End Results program, found that after adjusting for both clinical and socioeconomic conditions—like differences in access to care, stage at diagnosis, insurance status, and attitudes of health care providers—blacks were significantly less likely to survive colon, breast, uterine, bladder or head and neck cancer than whites.
Now, a team of medical and radiation oncologists from the University of Maryland Marlene and Stewart Greenebaum Cancer Center in Baltimore and Harvard Medical School’s Dana-Farber Cancer Institute in Boston have turned up an unexpected reason for the poor survival of blacks with head and neck cancer. Reporting in the September Cancer Prevention Research, the researchers, who began looking at the survival differences among blacks and whites for all head and neck cancers, noticed that the survival difference after chemotherapy and radiation treatment was much more pronounced when they focused just on oropharyngeal cancer.
“It was [a] statistical outlier and we really wanted to know why,” says oncologist Kevin Cullen, the study’s leader. After testing tumor samples from 201 patients for the presence of human papillomavirus-16 (HPV-16), which has been definitively linked to oropharyngeal as well as cervical cancers, the team had its answer. Patients, regardless of skin color, are five times more likely to survive if they have tumors that tested positive for HPV-16. Because many more whites have the HPV-positive tumors, more whites than blacks are still alive five years after their diagnoses.
“We don’t know why, but it’s clear from the results that patients whose tumors are caused by HPV are much more responsive to treatment with chemoradiation than those whose tumors are caused by other factors,” says Cullen. “Biologically, HPV-positive and HPV-negative tumors have markedly different behavior, the key difference [being] that HPV-positive tumors are much more treatable.” Specifically, 80 percent of whites with HPV-positive tumors in the study were alive five years after diagnosis compared with less than 30 percent of both whites and blacks with HPV-negative tumors. There were too few blacks with HPV-positive tumors to determine their survival rate.
Sexual habits in young teens may explain why blacks and whites have such different rates of HPV-positive tumors, says hematologist-oncologist Otis Brawley, the chief medical officer of the American Cancer Society. According to a study by the Centers for Disease Control and Prevention, adolescent blacks are much more likely than whites to have genital sex before they have oral sex. Getting a genital HPV infection provokes an immune response that protects a person from a subsequent oropharyngeal HPV infection because the immune response acts like a vaccination. “The lesson here isn’t to have oral sex early because then you’ll get the good kind of cancer,” says Brawley. “The lesson is that perhaps we should [be] vaccinating boys as well as girls against HPV and thinking about more aggressive surgical treatments for HPV-negative tumors.”
Brawley also points out that when it comes to cancer research, it’s important to look more than skin-deep. “The other lesson from these kinds of studies is that we should always be thinking about sociocultural factors that can explain black-white differences, instead of just ending the discussion at race.”