New research from Denmark, presented at the 31st Conference of the European Society for Radiotherapy and Oncology (ESTRO31), 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.

Dr. Lassen declared:

“We consider the present findings an important contribution to the ongoing debate on how to treat patients according to known independent prognostic factors, in this case tumor HPV-status and smoking history. These findings confirm the highly significant independent influence of HPV status on tumor control and survival in advanced oropharyngeal cancer that is treated with radiotherapy alone, without chemotherapy.

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

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.

Dr. Lassen explained:

“Although HPV status is known to be an independent prognostic factor determining tumor control and survival in radiotherapy for head and neck cancer, it is still not clear what the best treatment is for these patients. Data from the DAHANCA randomized trials has given us the opportunity to look at a group of patients, with known HPV and smoking status, who received radiotherapy without chemotherapy.”

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.

Dr. Lassen comments:

“This will give us important information. In the meantime, we will try to identify more patients with advanced oropharyngeal cancer and known smoking status in the DAHANCA database, in order to enlarge the present cohort, making the data more robust.”

President of ESTRO, Professor Vincenzo Valentini, a radiation oncologist at the Policlinico Universitario A. Gemelli in Rome, Italy, declared:

“This study confirms the highly significant independent influence of HPV expression on tumor control and survival in advanced oropharyngeal cancer treated with radiotherapy, with larger benefit in non-smoking patients, even in a non-chemotherapy setting. This study suggests it would be worthwhile testing the use of a moderately accelerated radiotherapy schedule as a single modality in these patients.”

Written By Petra Rattue