Prognosis of HPV-Positive Head and Neck Cancer Varies According to Tumor Site
Patients with cancer of the throat and who are positive for the human papillomavirus (HPV) have a good prognosis, but until now the effect of being HPV-positive on the prognosis of tumors located elsewhere in the head and neck was unknown. A new study presented at the 33rd Conference of the European Society for Radiotherapy and Oncology has shown that HPV status appears to have no prognostic effect on the outcome of primary radiotherapy in head and neck cancer outside the oropharynx.
According to Pernille Lassen, MD, PhD, of the Aarhus University Hospital, Denmark, head and neck cancers located outside the oropharynx should probably not be treated with the less-intensive treatment strategies that are currently being investigated in clinical trials for HPV-positive oropharyngeal tumors.
“HPV status has a very potent prognostic impact in radiotherapy for oropharyngeal cancer, and DNA from HPV has been found in all types of head and neck cancer, although it is far more common in oropharyngeal tumours. We decided to investigate the impact of HPV status in nonoropharyngeal cancers in the DAHANCA database, which includes all Danish head and neck cancer patients,” Dr. Lassen said.
Study Details
The researchers searched the database to identify patients with locally advanced cancers who had been treated primarily with radiotherapy, and identified 1,606 patients with larynx and pharynx carcinomas. Overall, 40% of the tumors were HPV-positive, and the frequency was significantly higher in oropharyngeal cancer (57%) than in nonoropharyngeal cancer (13%).
“In nonoropharyngeal cancers we found no prognostic impact of being HPV-positive in any of these endpoints,” Dr. Lassen said. “This indicates that HPV status does not help us in predicting response to treatment, and hence the outcome of these cancers.
Understanding the Underlying Mechanisms
“We know from laboratory studies that HPV-positive tumor cells are much more sensitive to radiation therapy than HPV-negative cells, so until now we believed that they would behave similarly irrespective of site,” Dr. Lassen said. “However, these data indicate that this is not the case, and at present we do not understand why this should be, though it probably can be ascribed to other biologic/genetic differences between the tumors rather than the HPV status. We would now like to try to elucidate the underlying mechanisms behind these different outcomes.”
There could be, for example, biologic and/or genetic differences between the tumors other than the HPV status, the researchers said. For example, genetic changes might be caused by smoking tobacco or due to tumors of mixed make-up, or simply differences due to the tumor site. “Such tumors with a combination of causes represent a challenge in our clinical daily practice,” Dr. Lassen said.
“We have started following up our work by analyzing all the tumor samples using polymerase chain reaction.... We hope this will enable us to understand more about why the role of HPV in nonoropharyngeal tumours is so different. There are few data available on this subject at present, so finding out will be an important step toward optimizing treatment for these patients,” he added.
Vincenzo Valentini, MD, the President of ESTRO and a radiation oncologist at the Policlinico Universitario A. Gemelli, Rome, Italy, commented, “These findings will have an important impact on the treatment of HPV-positive head and neck cancers, and are likely to lead to a change in current practice.”
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