New research from Denmark, presented at the 31st Conference of the European Society for Radiotherapy and Oncology , revealed that even though the human papilloma virus (HPV) can trigger throat cancer, non-smoking or light smoking HPV-positive patients respond well to radiotherapy treatment alone without requiring harmful chemotherapy in addition.
Dr Pernille Lassen, a resident in medical and radiation oncology and researcher at the University Hospital in Aarhus, Denmark said that the study findings demonstrated that in comparison with HPV-negative patients, those who were HPV-positive with advanced oropharyngeal cancer were observed to have considerably better control of the tumor at its primary site, disease-specific survival after five years and overall survival. After analyzing the patients' smoking history, the team found that HPV-positive patients who smoked the equivalent of 20 cigarettes a day for less than ten years had better results than HPV-negative patients who smoked the same amount for longer than 10 years.
Oropharyngeal cancer, i.e. cancer of the oropharynx or throat, including the soft palate and base of tongue is a relatively rare form of cancer, caused mainly by smoking and heavy drinking. The tumor can be triggered by HPV, yet poor diet is also linked to a higher risk. According to the International Agency on Cancer, every year, about 400,000 people worldwide are diagnosed with lip and oral/pharyngeal cancers.
By using data from the Danish Head and Neck Cancer Group (DAHANCA) database, Lassen and her team evaluated the results from 181 patients with advanced oropharyngeal cancer, i.e. cancer that had metastasized to the lymph nodes and beyond, who were treated between 1992 and 2005. The patients underwent accelerated radiotherapy treatment consisting of six fractions of radiation over a five-day period to shorten the overall treatment time. In conjunction with the radiotherapy, the patients also received Nimorazole, a radiotherapy-sensitizing agent that makes cancer cells more receptive to the effects of radiation, but no chemotherapy. To establish the patients' HPV status, the researchers analyzed samples of the tumor tissue.
103 of the 181 patients, or 57% were diagnosed with HPV positive tumors. The findings demonstrated that 81% of HPV-positive patients had better control of the tumor at its primary site, compared with 48% of HPV-negative patients, whilst disease specific survival and the overall survival rate for HPV-positive patients were 90% and 77%, compared with 56% and 38% respectively in those who were HPV-negative. After accounting for the participants' smoking history, the team observed that non-smoking HPV-positive patients or light smokers had considerably better outcomes, with a probability of tumor control at its primary site of 91%, disease-specific survival 96% and overall survival of 90% after their radiotherapy treatment was completed, compared with HPV-positive heavy smokers, who scored 77%, 81% and 63% respectively after 5 years.
Of those with HPV-negative tumors, all except for two of the 78 patients had a smoking history of 20 cigarettes a day for longer than 10 years. Regardless of how many years they smoked, their results were considerably worse, with a disease-specific survival of 50 to 52%, compared with those of HPV-positive patients. The DAHANCA 19 trial, as well as various other randomized trials are currently investigating treating patients according to their respective HPV status.