Moderately Hypofractionated Intensity Modulated Radiotherapy (IMRT) With a Simultaneous Integrated Boost for Locally Advanced Head and Cancer – Do Modern Techniques Held Their Promise?

Abstract PurposeIntensity-modulated-radiotherapy (IMRT) is still a standard of care for radiotherapy in locally advanced head and neck cancer (LA-HNSCC). Simultaneous-integrated-boost (SIB) and moderately hypofractionation offer an opportunity of individual dose painting and reduction of overall treatment time. We present retrospective data on toxicity and local-regional-control of a patient cohort with LA-HNSCC treated with an IMRT-SIB-concept in comparison to normofractionated 3D-conformal radiotherapy (3D-RT) after a long-term follow-up.MethodsBetween 2012 and 2014, n=67 patients with HNSCC (stages III/IV without distant metastases) were treated with IMRT-SIB either definitive (single/total doses: 2.2/66Gy, 2.08/62.4Gy, 1.8/54Gy in 30 fractions) or in the postoperative setting (2.08/62.4Gy, 1.92/57.6Gy, 1.8/54Gy). These patients' clinical course was matched (for gender, primary, and treatment concept) as part of a matched-pair-analysis with patients treated before mid-2012 with normofractionated 3D-CRT (definitive: 2Gy/50Gy followed by a sequential boost up to 70Gy; postoperative: 2Gy/60-64Gy). Chemotherapy/immunotherapy was given concomitantly in both groups in the definitive situation (postoperative dependent on risk factors). Primary endpoints were acute and late toxicity; secondary endpoint was loco-regional-control (LRC).Results67 patients treated with IMRT-SIB (n = 20 definitive, n = 47 adjuvant) were matched with 67 patients treated with 3D-RT. There were minor imbalances between the groups concerning non-matching-variables like extracapsular extension (ECE) and chemotherapy in IMRT-SIB.Significantly less toxicity was found in favor of IMRT-SIB concerning dysphagia, radiation dermatitis, xerostomia, fibrosis, and lymphoedema. After a median follow-up of 63 months, median LRC was not reached (IMRT-SIB) vs. 69.5m (3D-RT) (p=0.63).ConclusionThis moderately hypofractionated IMRT-SIB-concept showed to be feasible with less toxicity compared to conventional 3D-RT in this long-term follow-up observation.