CHICAGO, IL— Reduced-dose intensity-modulated radiotherapy (IMRT) after complete clinical responses to induction chemotherapy for operable stage III/IVA, human papillomavirus (HPV)-positive head and neck cancer appears to be safe and might improve patients’ quality of life, according to research presented at the 2014 American Society of Clinical Oncology (ASCO) Annual Meeting.
“Treatment for head and neck cancer can be quite grueling, so it’s very encouraging to see we can safely dial back treatment in patients with less aggressive disease and an overall good prognosis, particularly for young patients who have many years to deal with the long-term side effects,” said lead study author Anthony Cmelak, MD, professor of radiation oncology at Vanderbilt-Ingram Cancer Center in Nashville, TN. “However, we need longer follow-up, as well as confirmatory phase 3 data, before we can recommend applying this strategy in practice.”
Low-dose (54 Gy) IMRT resulted in a two-year progression-free survival (PFS) of 80%, Dr. Cmelak said. “Patients with minimal smoking history did exceptionally well, with a 92% PFS and 97% two-year survival rate.”
A total of 80 eligible patients with operable stage III/IVA HPV-positive oropharyngeal squamous carcinoma underwent induction chemotherapy with paclitaxel, cisplatin, and cetuximab. Of these, 62 patients had complete clinical response and were administered 54 Gy of IMRT. Patients without complete clinical responses following induction therapy received a standard radiation dose IMRT of 70 Gy.
The reduced-dose IMRT regimen was associated with high tumor control rates and minimal late toxicities, Dr. Cmelak said. The “biggest factor in outcome” was smoking history of less than 10 pack-years, Dr. Cmelak said. “The best outcomes were seen in patients with little smoking history, no bulky tumor burdens and no contralateral tumors.”
Reducing the radiation dose should offer patients decreased risk of late effects, such as trouble swallowing, dry mouth, loss of taste sense, thyroid problems and muscular stiffness, he noted. The reduced-dose IMRT would not be suitable for patients with HPV-negative disease, Dr. Cmelak said.
Approximately 70% of newly-diagnosed oropharyngeal cancers are related to HPV infection. Patients with HPV-positive tumors have better outcomes than those with HPV-negative tumors.
- Cmelak A, Li S, Marur S et al. Abstract LBA6006. Presented at: 2014 ASCO Annual Meeting; May 30-June 3, 2014; Chicago, IL.