The research was presented by lead author Anthony Cmelak, M.D., professor of Radiation Oncology at Vanderbilt-Ingram Cancer Center (VICC), during the 50th annual meeting of the American Society of Clinical Oncology (ASCO), held recently in Chicago.
The study focused on patients with newly-diagnosed oropharyngeal cancers related to the human papilloma virus (HPV). More than two-thirds of new head and neck cancer patients have HPV-positive tumors and the number of these patients is on the rise. Cmelak's prior cooperative group study found that patients with HPV-positive oropharyngeal cancer have significantly longer survival rates than patients whose tumors are HPV negative.
For the new study, 80 HPV-positive patients with stage III, or IVa,b squamous cell cancer of the oropharynx received induction chemotherapy, including paclitaxel, cisplatin and cetuximab.
After chemotherapy, 62 of the patients showed no sign of cancer and were assigned to receive a 25 percent lower dose of intensity-modulated radiation therapy - an advanced technology that targets the radiation beam more accurately to treat the tumor without harming surrounding tissue. The rest of the patients received a standard IMRT dose. The drug cetuximab was also given to both groups of patients along with the IMRT treatment.
Two years after treatment, the survival for the low-dose IMRT patients was 93 percent. Those who did not have complete resolution of cancer following induction and went on to get full-dose radiation had an 87 percent two-year survival. Eighty percent of the low-dose patients and 65 percent of standard IMRT patients also showed no evidence of tumor recurrence. Ninety-six percent of those who had minimal or no smoking history had no evidence of tumor recurrence after two years following treatment, and long-term side effects were minimal.
The investigators concluded that patients with HPV-positive cancer who had excellent responses to induction chemotherapy followed by a reduced dose IMRT and cetuximab experienced high rates of tumor control and very low side effects particularly for those with a minimal smoking history.
Treating tumors in the delicate head and neck region often causes side effects that can be troublesome and long-lasting, including difficulty swallowing, speech impairment, dry mouth, problems with taste and thyroid issues, so any therapy option that reduces these side effects can have an impact on patient quality of life.
"Treatment for head and neck cancer can be quite grueling, so it's very encouraging to see we can safely dial back treatment for patients with less aggressive disease and an overall good prognosis, particularly for young patients who have many years to deal with long-term side effects," said Cmelak.
He noted that lower-dose IMRT is not recommended for patients with HPV-negative cancer or larger tumors.
The authors note that further studies of reduced-dose IMRT in HPV-positive patients are warranted.
Other investigators include Jill Gilbert, M.D., VICC; Shuli Li, Ph.D., Dana Farber Cancer Institute, Boston, Massachusetts; Shanthi Marur, M.D., William Westra, M.D., Christine Chung, M.D., The Johns Hopkins University School of Medicine, Baltimore, Maryland; Weiqiang Zhao, M.D., Ph.D., Maura Gillison, M.D., Ph.D., The Ohio State University, Columbus, Ohio; Julie Bauman, M.D., Robert Ferris, M.D., University of Pittsburgh Cancer Institute; Lynne Wagner, Ph.D., Feinberg School of Medicine, Northwestern University, Chicago, Illinois; David Trevarthen, M.D., Colorado Cancer Research Program, Denver; A. Demetrios Colevas, M.D., Stanford University, California; Balkrishna Jahagirdar, M.D., HealthPartners and Regions Cancer Care Center, St. Paul, Minnesota; Barbara Burtness, M.D., Fox Chase Cancer Center, Philadelphia, Pennsylvania.
Funding was provided by The National Cancer Institute, a division of the National Institutes of Health (CDR0000665170).