HPV-positive oropharyngeal cancers respond well to radiotherapy

New findings from a large Danish database of cancer patients suggest that, although human papillomavirus (HPV) can trigger oropharyngeal cancer, patients who are HPV-positive and are light smokers or don't smoke at all respond well to treatment using radiotherapy without chemotherapy.

In a presentation May 10 at the 31st conference of the European Society for Radiotherapy and Oncology in Barcelona, Pernille Lassen, MD, PhD, a resident in medical and radiation oncology and researcher at Aarhus University Hospital, reported that HPV-positive patients with advanced oropharyngeal cancer had significantly better control of the tumor at its primary site.

These patients also had better disease-specific survival after five years and better overall survival than patients who were HPV-negative.

"Our results suggest that the use of radiotherapy alone may be a safe treatment strategy in patients who are light or nonsmokers, while sparing them the side effects associated with chemotherapy," Dr. Lassen said. "However, it is too soon to select patients for a specific treatment based on these factors; we still need more data."

Dr. Lassen and her colleagues investigated the outcomes of 181 patients in the Danish Head and Neck Cancer Group database who were treated between 1992 and 2005 for advanced oropharyngeal cancer. The patients received accelerated radiotherapy together with Nimorazole, an agent that acts as a radiotherapy sensitizer. No chemotherapy was given. Samples of tumor tissue were analyzed to establish HPV status.

Of the 181 patients, 103 had HP- positive tumors (57%). The researchers found that these HPV-positive patients had better control of the tumor at its primary site (81% versus 48% of HPV-negative patients), disease-specific survival (90% versus 56%), and overall survival (77% versus 38%).

When the researchers took smoking history into account, HPV-positive (light or nonsmokers) patients had very favorable outcomes, the researchers reported. The probability of tumor control at its primary site was 91%, disease-specific survival was 96%, and overall survival was 90% five years after completion of radiotherapy. In comparison, the corresponding results for HPV-positive heavy smokers were 77%, 81%, and 63% after five years.

All but two of the 78 patients with HPV-negative tumors had a smoking history of more than 10 pack years, and their outcome was significantly worse than HPV-positive patients, regardless of pack years, the study authors found. Disease-specific survival in this group was around 50%.

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