- Most of the oropharyngeal cancers are fueled by the human papilloma virus (ḪPV) which is found to release two proteins E6 and E7.
- In patients with oropharyngeal cancer recurrence, the levels of E7 antibody did not decrease as quickly over time as compared to those patients in whom cancer did not recur.
Chances of predicting the recurrence of head and neck cancers at early stage has been made possible by the discovery of two blood-based markers.
Oropharyngeal cancer is a type of head and neck cancer which occurs in the throat, tonsils and back of the tongue or lungs. Most cases of this cancer is caused by the human papilloma virus (ḪPV).
Surgery is the best treatment option for this cancer which can eliminate the disease. Once the cancer spreads to the lungs, targeted therapies might improve outcomes if applied early.
There are no known biomarkers to predict the treatments failure risk yet. But in a new study, researchers have found, what could be potential blood-based markers to predict risk of cancer recurrence.
In most cases of HPV related cancer, the presence of two proteins E6 and E7 are found. Researchers observed that among patients with oropharyngeal cancer, the level of antibodies for these two proteins are higher.
Measuring Antibody Levels
Researchers recruited 52 patients with advanced oropharyngeal cancer. Among them, 22 patients had developed recurrence and 30 had not. All cases were HPV-related.
Initially after treatment, patients in both groups showed a decline in E6 and E7 antibody levels. Since oropharyngeal cancers almost never recurs three months after treatment, all patients showed a decline in antibody levels.
On an average, recurrence occurred at 13 months after the treatment.
"Most patients recur within the first two years, so the window to catch it is two years after treatment. Everyone's level goes down over time, but some start to go up a little and those are the ones we have to focus on," says study author Matthew E. Spector, M.D., assistant professor of otolaryngology at the University of Michigan Health System.
Predicting Risk By Antibody Levels
On observing the levels of E6 and E7 antibodies over time, researchers found that the levels of E7 antibody was not decreasing as quickly in patients whose cancer recurred. The detection was made prior to the point when the recurrence was discovered.
"If we can monitor someone through blood markers, then instead of a patient coming for a clinic visit every two to three months, they could get blood drawn near home. If there's evidence of high E7, we can tell the patient to come in for more evaluation," Spector says.
The level of antibodies varies with people and the absolute level was not an indication.
"It's very patient-specific," Spector says. "Each patient will have different levels, but the question is what happens when you track it over time. If it rises, that suggests recurrence."
It will be inexpensive and easy to implement the test for E6 and E7 antibodies as it is a standard laboratory test that could be performed at any cancer treatment facility. Large scale testing is needed to confirm the findings.
The findings are published in Clinical Cancer Research.
- Matthew E. Spector et al. E6 and E7 antibody levels are potential biomarkers of recurrence in patients with advanced stage human papillomavirus positive oropharyngeal squamous cell carcinoma. Clinical Cancer Research; (2016) DOI: 10.1158/1078-0432.CCR-16-1617