Grant: Project Grant

Oropharyngeal carcinoma (OPC) is the most common type of head and neck cancer and ninth most common cancer in Canadian men. Most OPCs are associated with the human papilloma virus (HPV) and have a good prognosis. The primary treatment is usually radiation therapy (RT). Although less than 15% have obviously involved lymph nodes on the opposite side of the neck, most patients receive RT to both sides of the neck because of the concern that microscopic cancer cells could spread to the opposite side. This approach increases the risk of swallowing impairment, dry mouth, and temporary feeding tube insertion, as compared to treatment of only one side of the neck. Lymphatic mapping with Single Photon Emission Computed Tomography (SPECT-CT) imaging may help to identify whether an OPC is at risk for spread to the opposite side of the neck and, if so, the specific areas that are at risk for nodal disease. Lymphatic mapping is performed by injecting a radioactive tracer around the tumour, followed by capturing the distribution of the tracer to the lymph nodes of the neck. Patients will be randomized to either lymphatic mapping-guided RT or to standard bilateral neck RT. In patients randomized to the lymphatic mapping-guided treatment and in whom the radiotracer only migrates to the same side of the neck, RT will be limited to that side. In those patients in whom the radiotracer migrates to the opposite side of the neck, only the regions of the neck to which the radiotracer migrates will receive radiotherapy. We anticipate that this personalized treatment based on lymphatic mapping will provide similar cancer control, but will reduce side effects and improve quality of life compared to routinely treating both sides of the neck. We will evaluate the cost-effectiveness of this new approach and expect that it will offer a safe, effective, and cost-effective standard of care to patients in Canada and across the world.