According to research presented at the 2014 Multidisciplinary Head and Neck Cancer Symposium, steering clear of the contralateral submandibular gland during radiation therapy is very much a possibility and safe with advanced stage, node positive head and neck cancers and base of tongue lesions.
Researchers from the University of Colorado Cancer Center and the Memorial Sloan-Kettering Cancer Center conducted a retrospective analysis of 71 patients from the two facilities. The average patient age was 55, and approximately 50 percent of the patients were current or former smokers.
Forty patients had primary tonsil cancers, and 31 patients had tumors that involved the base of the tongue. Around 80 percent of patients had N2b or greater disease (translating in extensive lymph node involvement), and 90 percent of patients had overall stage IV disease (pointing to advanced cancer). The analysis only included patients who were undergoing treatment to the bilateral neck.
All of the patients had been treated with radiation methods that avoided the contralateral submandibular gland (cSMG), which points out that it was on the opposite side of the neck as the cancer. Submandibular glands are major salivary glands found under the floor of the mouth and are in charge for the majority of unstimulated salivary flow. The average dose to the cSMG was 33.04 Gy, and at an average follow-up of 27.3 months, no patients had experienced recurrences in the contralateral level Ib lymph nodes (the area of the spared submandibular 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 lead author of the study and an MD candidate in his final year at the University of Colorado School of Medicine, Tyler Robin, PhD.
"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."