- In HPV-associated cancer of the oropharynx, the immune system responds by producing antibodies against a human papillomavirus type 16 (HPV16) protein E6.
- These antibodies against HPV16 E6 are regarded as very valuable biomarkers of oropharyngeal cancer and can be detected in the blood samples of patients, long before the clinical symptoms manifest.
- A single blood sample taken at any point of time might be sufficient for assessing a person's risk for developing cancer of the oropharynx for many years.
An antibody test for early detection if a person has a very high risk of developing an HPV-associated cancer of the oropharynx has been developed.
In the U.S, cancer of the oropharynx has become increasingly common and the number of newly diagnosed cases has tripled over the past three decades. About 70% of these tumors are caused by infection with human papillomavirus (HPV) type 16.
The test has been developed by Tim Waterboer and his colleagues at the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) in Heidelberg.
The immune system responds to an infection with HPV by producing antibodies against components of the virus. The chronically infected cells produce a HPV protein E6 (HPV16 E6) that plays an important role in the development of cancer.
Antibodies produced against HPV16 E6 are regarded as very valuable indicators of oropharyngeal cancer.
For the early cancer detection study, approximately 150 000 healthy participants were recruited between 1993 and 2001, and cancers that they developed in the period under investigation were documented.
Around 198 blood samples from patients with tumors of the oropharynx were studied. The samples had been taken when the participants entered the study, long before the onset of the disease. The control samples comprised 924 participants without cancer diagnosis.
The antibodies against HPV16 E6 were detected in the blood samples of 42.3% of the patients with oropharyngeal cancer. In the control group, only 0.5 percent of individuals tested positive to HPV16 E6. Only those patients whose cancer was associated with HPV, tested positive for the HPV16 E6 antibodies.
"This pretty much corresponds to the percentage of HPV-related cases of oropharyngeal cancer that we expected to find for that time in the American population," Tim Waterboer said.
The findings also revealed that if the test result for HPV16 E6 antibodies is positive once, it remains stable over many years.
"This means that a single blood sample test taken at any point of time might be sufficient for assessing a person's risk for developing cancer of the oropharynx within the next 10 years," said Waterboer.
The detection of HPV16-E6 antibodies is at present, not a suitable method for early cancer detection in larger population groups.
"The occurrence of new cases of oropharyngeal cancer is rather low at about five cases per 100 000 inhabitants," said Waterboer, who is the study head. "That means that although the test is highly specific, very many healthy people would receive false positive results. However, in certain high-risk groups, up to ten times more people can develop the disease. HPV16 E6 antibody detection is the first ever easy-to-analyze biomarker that enables us to narrow down the circle of individuals who are at an extremely high risk of developing the cancer."
The test for antibodies against HPV16 E6 is not suitable for assessing the risk for HPV-associated cervical cancer, and other cancers in genital areas. This is because the revealing antibodies do not occur in the genital areas before the cancer becomes clinically detectable.
The findings are reported in the Journal of the National Cancer Institute.
- Tim Waterboer et al. Kinetics of the Human Papillomavirus Type 16 E6 Antibody Response Prior to Oropharyngeal Cancer. Journal of the National Cancer Institute; (2017) DOI: https:doi.org/10.1093/jnci/djx005