SBRT after Conventional IMRT in Locally Advanced/Recurrent Head and Neck (HN) Cancers: Importance of Patient Selection

PURPOSE/OBJECTIVE(S) There is limited data on the use of SBRT for salvage or consolidative treatment of Head and Neck cancers. Given the relatively poor prognosis for recurrent HN cancers and risk of toxicity with the addition of hypofractionated RT after conventional IMRT, we wanted to evaluate patients that should receive SBRT. MATERIALS/METHODS Patients with HN cancer treated in Radiation Medicine were selected and data collected using a data extraction software. This data extraction software collects data from electronic medical records at a large tertiary care academic medical center. Consecutively treated patients with adequate documentation were selected. Data gathered included primary sites of cancer, the initial total dose from conventional treatment, number of fractions, SBRT total dose and fractions, metastatic disease or locoregional progression, types of grade 3-5 toxicity (CTCAE v four toxicity), time to develop toxicity and progression and time since SBRT to last follow-up. Time to toxicity was estimated using the Kaplan-Meier product limit method, and each factor was compared using the log-rank test. RESULTS Median age was 69 (Range 39-90). The median time between EBRT/ChemoRT and SBRT was six months (1-108 months). There were 59 males (71%) and 24 females (29%). The primary HN sites included oropharynx (OP) (37%), oral cavity (OC) (24%), hypopharynx, neck, salivary gland, paranasal sinus, and larynx cancers. The most common histology was squamous cell cancers, although less common histologies include salivary duct adenocarcinoma and esthesioneuroblastoma among others. Ten patients (12%) received SBRT after surgical resection of recurrence. Thirty-four patients (41%) were censored alive at / = 12 months developed grade 3 or 4 toxicity while 16 of 47 (34%) developed grade 3/4 toxicity with follow-up 5, P = 0.0114), post-op SBRT (P = 0.0018) and the interval between EBRT/CRT and SBRT (P = 0.02). There was field overlap between EBRT and SBRT in all patients. Adverse outcomes include necrosis, fistula, stomal bleeding, seizure, intractable pain, and PEG dependence. CONCLUSION SBRT after full dose EBRT should be used in select patients given its toxicity and limited survival in patients with advanced/locally recurrent head and neck cancer. We are planning a prospective evaluation of the use of SBRT in recurrent/locally advanced settings.