Unilateral Radiotherapy for Advanced Tonsil Cancer Yields Favorable Outcome
New research suggests that it is safe to limit radiation therapy to lymph nodes on only one side of the neck for lateralized tonsil cancer. In addition, the study findings show that primary tumor location, rather than the amount of lymph node involvement on the tumor side of the neck, drives the risk of cancer spread to the opposite side of the neck. The study by Hwang et al was presented at the 2014 Multidisciplinary Head and Neck Cancer Symposium.
Study Methodology
The study involved 153 patients with squamous cell carcinoma of the tonsil who were treated with surgical resection and postoperative intensity-modulated radiation therapy between 1997 and 2012. Thirty patients also received concurrent chemotherapy. The study focused on 46 of the patients who had received unilateral radiotherapy; of these, 40 patients (87%) had lateralized primary tumors, 2 patients (4%) had nonlateralized primary tumors, and lateralization could not be determined retrospectively in 4 patients (9%).
Of the 46 patients who were treated unilaterally, 72% were men, and the average patient age was 59. Sixty-one percent of patients were current or former smokers, and 33 patients (72%) were p16 immunohistochemistry positive. T-stage was classified as TX in one patient (2%), T1 in 20 patients (44%), T2 in 19 (41%), and T3 in 6 patients (13%). The patients’ stages of lymph node involvement were N0 in 5 (11%), N1 in 6 (13%), and N2 in 35 (76%).
Patients received radiation doses of 60 to 66 Gy to the postoperative bed and involved neck and 52 to 54 Gy to the elective neck in 30 to 33 fractions using a simultaneous integrated boost technique.
Study Findings
There were no local or regional recurrences in the patients treated with unilateral radiotherapy after a median follow-up of 2.8 years (range, 0.4–8.7 years). Distant metastasis developed in four (9%) of the patients, and two patients developed second primary cancers.
According to the study authors, the results support the concept that the location of the tonsil cancer, rather than ipsilateral neck N stage, dictates the risk for disease in the contralateral neck.
The study results also show that for appropriately selected patients with tonsil cancer, the volume of radiation needed to control the cancer can be significantly reduced, limiting treatment side effects and toxicities.
“From the patient’s perspective, the less normal tissue that’s treated translates directly to less toxicity both during treatment and for the rest of their lives,” study author Wade L. Thorstad, MD, Chief of Head and Neck Services and Associate Professor of Radiation Oncology at Washington University School of Medicine in St. Louis, said at a news briefing. “We would like to see additional studies and follow-ups that confirm these results.”
The study authors reported no conflicts of interest.
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