Low-dose IMRT may be safe for HPV-positive head/neck cancer patients

Lower-dose radiation intensity-modulated radiation therapy (IMRT) may be safe for some patients with human papillomavirus (HPV)-positive oropharyngeal cancer, according to a study presented at the American Society of Clinical Oncology annual meeting in Chicago. This may offer patients a better quality of life by decreasing the risk of debilitating, often long-term side effects, such as difficulty swallowing, dry mouth, loss of taste, neck stiffness, and thyroid problems, the researchers noted.

The phase II study enrolled 90 patients (median age 57 years) who received induction chemotherapy with paclitaxel, cisplatin, and cetuximab. Patient's response to induction chemotherapy determined the IMRT dose they received. Sixty-two patients with operable stage III/IVA HPV-positive oropharyngeal squamous carcinoma who had a complete clinical response received a reduced dose (54 Gy) of IMRT; the other 28 patients received standard-dose IMRT (70 Gy). All patients received standard cetuximab along with radiation.

Overall two-year survival and progression-free survival were 93% and 80%, respectively, among the 62 patients who received lower-dose IMRT, according to lead study author Anthony Cmelak, MD, a professor of radiation oncology at Vanderbilt University and the medical director of the Vanderbilt-Ingram Cancer Center.

Among the patients who received low-dose IMRT, survival was slightly higher for those with less than 10 pack years of smoking and earlier-stage disease; in those patients two-year progression-free and overall survival were 92% and 97%, respectively. Outcomes were worse for the higher-risk patients treated with the standard IMRT dose; two-year overall survival and progression-free survival were 87% and 65%, respectively.

Lower-dose IMRT would not be suitable for patients with HPV-negative disease or larger tumors, Dr. Cmelak noted, adding that a large randomized trial is needed. He said the study represents evidence that physicians need to look at the optimal regimen for both chemotherapy and radiation technique and dosage to minimize toxicities.

The research was supported by the National Institutes of Health.