A Case of Metastatic Head and Neck Squamous Cell Carcinoma with Multiple Treatments Including Stereotactic Ablative Body Radiotherapy Alone for Oligometastases to the Parotid Gland.

Head and neck squamous cell carcinoma (HNSCC) has a reported average of around 15% metastases at presentation with chemotherapy being the mainstay of treatment for widely metastatic disease. However, in select patients with oligometastatic disease, local ablative therapy (commonly including surgery or radiotherapy) can be utilized with the possibility of improving survival, decreasing morbidity from the metastases, and obviating the need for systemic therapy with its possible side effects. However, most research has been of ablative therapy has been performed for pulmonary and hepatic oligometastatic lesions.  In this case, we present a patient who initially presented with a metastatic base of tongue malignancy with left axilla metastases who was treated palliatively with systemic therapy with an initial complete response. She subsequently progressed on maintenance therapy with a locoregional recurrence that was treated with definitive chemoradiation with complete response. There was a subsequent recurrence again in the left axilla that was treated as well with chemoradiation with complete response. Next, there was a recurrence in the right occipital lobe and left parotid gland with treatment with surgical resection, plus stereotactic radiotherapy boost and stereotactic ablative body radiotherapy (SABR), respectively. This all occurred over a 30-month time frame from initial therapy to her last treatment, with an additional 42 months at the present time with no recurrence.  This case highlights the future of care of oligometastatic disease of HNSCC with potential long-term survival in appropriately selected patients treated with stereotactic ablative body radiotherapy. Furthermore, this is one of the first reported cases in the literature of SABR for an oligometastatic lesion of the parotid gland, especially from squamous cell carcinoma (SCC) of the oral cavity, with no recurrence of disease over 40 months removed from treatment.