Role of reradiation in head and neck cancer from limits to option

Locoregional recurrence (LRR) or second primary malignancy in the previously treated area continues to be a major cause of treatment failure with significant morbidity and mortality in head and neck cancer. Prognosis of recurrent disease is dismal. To manage LRR is a therapeutic challenge for multidisciplinary head and neck team and more so if it is in a previously irradiated area. Though surgery is the mainstay of treatment but curative resection is feasible in only minority of patients. Systemic therapy alone has no long-term response rate or survival advantage in the management of inoperable recurrences. Full dose reradiation (RERT) with or without concurrent systemic therapy (CRERT) remains the only viable treatment option offering long-term survival in carefully selected patients. RERT is not a new concept but traditionally been avoided because of concern regarding toxicity due to limitations of conventional radiotherapy techniques. Initial studies were restricted to brachytherapy with its limitations. During the past two decades with the revolution in radiation therapy treatment delivery, more precise treatment techniques such as intensity-modulated radiation therapy, image-guided radiation therapy (IGRT), adaptive radiation therapy, stereotactic body radiotherapy, stereotactic radiosurgery, tomotherapy, intensity modulated proton therapy, image-guided brachytherapy in combination with better imaging modalities to define the target with the concept of biological target volume, offer various options for RERT with improved survival and limited toxicity. Pattern of failure even after full dose RERT is mainly infield, inside recurrent gross tumor volume (r GTV); radioresistance and tumor hypoxia may be the probable explanation. Though RERT has been established as a mainstream treatment option, there is a lack of prospective multi-institutional studies and absence of phase III randomized trial except one in adjuvant setting. Optimum treatment is yet to be defined. We have reviewed the literature and attempt has been made to provide guidance to the priorities on which future investigation should focus. There is a need to reevaluate prognostic factors for survival, selection criteria for patients undergoing RERT, measures to reduce the infield recurrence and morbidity, reradiation tolerance of normal tissue in IGRT era, toxicity antagonist and molecular marker as a diagnostic and prognostic tool. There is a need of multi-institutional prospective randomize trial with uniform data reporting.