Source: www.medpagetoday.com
Author: Michael Smith, North American Correspondent, MedPage Today

Patients with cancer of the oropharynx did significantly better if their tumor showed markers of human papillomavirus (HPV), a researcher said.

In a retrospective analysis of patients in a large chemotherapy trial, those with HPV-positive tumors had a five-year survival rate of 79% regardless of the type of treatment, according to Marshall Posner, MD, of the Dana-Farber Cancer Institute in Boston.

In contrast, those whose tumors were HPV-negative had a five-year survival rate of just 31% — a difference that was statistically significant at P<0.0001, Posner said in a poster discussion session at the annual meeting here of the American Society of Clinical Oncology.

The pattern was similar for progression-free survival, Posner told MedPage Today.

The two groups were significantly different in several ways, he said, including age, T-stage, and performance status, suggesting that HPV-positive cancers are a different clinical entity from environmentally driven HPV-negative cancers.

One possible clinical implication is that patients with HPV-positive tumors might be treated with lower doses of radiation, since they respond well to treatment, he said. “We might reduce the late consequent toxicity (of radiation) – the scarring, the fibrosis, the dry mouth, the osteo-radionecrosis,” he said.

He noted that patients with HPV-positive tumors tend to be younger, and thus have longer to live with the consequences of therapy. “If we can reduce those effects, we would do a big boon,” he said.

The finding comes from an analysis of patients who took part in the TAX 324 trial, which looked at the effects in head and neck cancer of induction chemotherapy followed by concurrent chemoradiation. (See HPV Infection Linked to Survival in Some Head and Neck Cancers)

Of the patients with cancer of the oropharynx, Posner said, HPV status could be found for 111 of them after analysis of stored tissue samples, including 56 whose tumors were HPV-positive.

The HPV-positive patients, he said, were significantly more likely to be younger, Caucasian, have T1 or T2 primary tumors, and have a performance status of 0, at P=0.02, P=0.03, P=0.001, and P=0.003, respectively.

They also had an “enormous difference in overall survival that was almost entirely driven by a three-fold reduction in local-regional failure,” he said.

Indeed, he reported, only seven of the 56 HPV-positive patients had such a failure, compared with 23 of the 55 HPV-negative patients — a difference that was significant at P<0.0001.

The results add to the growing body of evidence that patients with HPV-positive head and neck cancer have significantly higher overall and progression-free survival, according to Anil Chaturvedi, DVM, PhD, of the National Cancer Institute, who was not part of the study but discussed it in an oral session.

The findings raise “profound” research questions – such as the exact mechanism responsible for the improved outcomes – as well as questions about the proper treatment course for such patients, he said.

“Given their better survival, this would argue for targeted therapies,” he said, including low-dose radiation.

The study was supported by Sanofi Aventis and the Dana-Farber Cancer Institute. Posner made no disclosures.

Source:
1. Posner MR et al. “Oropharynx cancer (OPC) in TAX 324: Human papillomavirus (HPV) and survival.” J Clin Oncol 28:7s, 2010 (suppl; abstr 5525)