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Limiting radiation to major salivary glands in head and neck cancer patients

Avoiding the contralateral during is feasible and safe with advanced stage, node positive head and neck cancers and base of tongue lesions, according to research presented at the 2014 Multidisciplinary Head and Neck Cancer Symposium.

Researchers conducted a retrospective analysis of 71 patients from two facilities – the University of Colorado Cancer Center and the Memorial Sloan-Kettering Cancer Center. The median patient age was 55, and about 50 percent of the patients were current or former smokers. Forty patients had primary tonsil cancers, and 31 patients had tumors involving the base of the tongue. About 80 percent of patients had N2b or greater disease (meaning extensive lymph node involvement), and 90 percent of patients had overall stage IV disease (indicating advanced cancer). The analysis only included patients who were receiving treatment to the bilateral neck.

All of the patients had been treated with radiation techniques that spared the contralateral gland (cSMG), which indicates it was on the opposite side of the neck as the cancer. glands are major salivary glands located beneath the floor of the mouth and are responsible for the majority of unstimulated salivary flow. The mean dose to the cSMG was 33.04 Gy, and at a median follow-up of 27.3 months, no patients had experienced recurrences in the contralateral level Ib lymph nodes (the area of the spared gland).

“Sparing the submandibular gland from radiation can decrease the side effect of dry mouth, which has a substantial impact on patients’ quality of life,” said Tyler Robin, PhD, lead author of the study and an MD candidate in his final year at the University of Colorado School of Medicine. “Historically, however, there has been hesitation to spare the submandibular gland from radiation because there are lymph nodes near the gland that also end up not getting treated. While this seems worrisome because head and neck cancer spreads through the lymph nodes, it is well established that the risk of cancer involvement in the lymph nodes near the submandibular gland is exceedingly low, yet the benefit of sparing the gland for a patient’s quality of life is high. It is important to consider treatment side effects alongside treatment benefit, and overall, our goal is to decrease side effects associated with radiation treatment without undertreating a patient’s cancer. With modern advances in radiation therapy, it is possible to eloquently treat cancers while avoiding surrounding normal tissues. Our study is a prime example of how we can safely spare normal tissue in appropriate patients in order to decrease treatment side effects.”


12: A Multicenter Experience in Contralateral Submandibular Gland Sparing in Head and Neck Radiotherapy: An Assessment of Feasibility and Safety

T. Robin1, G. Gan1, M. Tam2, D. Westerly1, J. Raben1, N. Riaz2, N. Lee2, D. Raben1, 1University of Colorado, Denver, CO, 2Memorial Sloan-Kettering Cancer Center, New York, NY

Background: Radiotherapy (RT) for head and neck cancer (HNC) treatment is associated with significant lifelong morbidity. Xerostomia, in particular, is a common side effect of HNC RT and it has a significant long-term impact on patient quality of life. In addition to discomfort, xerostomia is associated with poor oral and dental health as well as speech and swallowing. Long-term HNC RT side effects are of more concern now than ever as the epidemiology of HNC is changing with more younger, HPV-positive patients, many of whom will become long-term survivors of HNC. For many years, parotid gland sparing has been practiced to mitigate xerostomia, yet it is well established that although the parotid glands play a major role in stimulated saliva production, it is the submandibular glands that are responsible for the majority of un-stimulated salivary flow. Based on established head and neck lymph drainage patterns, it has been proposed that the contralateral submandibular gland (cSMG) can be spared in many HNC patients, regardless of nodal status, but there is a substantial lack of outcome data for patients treated with cSMG-sparing plans.

Methods and Materials: We retrospectively analyzed patients who were treated with cSMG-sparing techniques at the University of Colorado Cancer Center and at the Memorial Sloan Kettering Cancer Center. cSMG doses less than or equal to 39Gy were considered spared glands. Only patients receiving treatment to the bilateral neck were included in the analysis. Patients were not excluded based on T or N stages or overall stage.

Results: We identified 82 patients who were treated with cSMG-sparing treatment plans, with a median age of 56 years. Fifty percent of the patients were current or former smokers. The majority of patients had primary tonsil cancers (48 of 82 patients), followed by base of tongue lesions (BOT) (30 of 82 patients). Eleven patients had T3 or T4 tumors, 65 patients had N2 or N3 disease, and 80 patients had overall stage III or IV disease. Eighty patients were treated with concurrent chemoradiation therapy using intensity modulated techniques. The mean dose to the cSMG was 32.54Gy and at a median follow-up of 27.4 months there were no patients who had recurrences in the contralateral level Ib lymph nodes.

Conclusions: This is one of the largest series reporting on submandibular sparing in locally advanced HNC. These results are preliminary evidence that cSMG-sparing is feasible technically, and that cSMG-sparing is safe even in advanced stage, node positive cancers as well as in BOT lesions. These outcome data offer significant promise for decreasing morbidity in HNC patients, especially young, HPV-positive patients who will in many cases go on to live decades beyond their definitive cancer treatment.

Author Disclosure Block: T. Robin: None. G. Gan: None. M. Tam: None. D. Westerly: None. J. Raben: None. N. Riaz: None. N. Lee: None. D. Raben: None.

American Society for Radiation Oncology