Contemporary swallowing outcome for oropharynx carcinoma following definitive VMAT (chemo)radiotherapy

Abstract

Introduction: Increasingly conformal radiotherapy with smaller treatment volumes has reduced acute and late toxicity following treatment for head and neck SCC (HNSCC). Limited prospective data on toxicity for unselected patients receiving modern therapy outside of the trial setting is published. We report swallow outcome for oropharynx cancer following definitive (CT)RT up to three years post treatment and assess the effect of evolving radiotherapy practice over the period. Materials and Methods: A Speech and Language Specialist performed MDADI and PSS normalcy of diet at baseline and when followed up at 3–6 months, 12 months and 36 months (if patients three years post treatment at time of analysis) for oropharynx patients referred for definitive (CT)RT from Mar 2016- Jan 2020 from a single MDT. Photon radiotherapy was delivered via a VMAT technique to a dose of 66 Gy in 30 fractions, plus chemotherapy when indicated according to international practice. Initially treatment volumes routinely included GTV + 1 cm to high dose and entire oropharynx to intermediate/low dose. Over time standard volumes reduced to an expansion of 0.5–1 cm from GTV to form high dose CTV and no subsite irradiation. Patients with a previous HNSCC or who recurred following treatment were excluded from analysis. Wilcoxon rank sum test was applied to test swallow outcome for patients treated with or without sub-site irradiation. Results: 117 patients were identified. 16 patients relapsed during follow up and were excluded from analysis. Median age was 59 (range 30–81), 77% male, 88% PS0–1, 69% current or ex- smokers. 90% had stage III-IV disease and CTRT was received by 75%. 4% of patient required a RIG prior to therapy and 51% received a reactive NG tube during therapy. At baseline, 3–6 months, 12 months and 36 months MDADI and PSS scores were 79, 67, 76, 88 and 88, 65, 77, 84 respectively. RIG dependency at 1 year was 2.8% (reasons: 1 aspiration, 1 severe dysguesia, 1 severe xerostomia), and 0% in the minority of patients with 3 year assessment performed. Sub-site irradiation was associated with an 18 point lower PSS (p = 0.02) and 9 point lower MDADI score (p = 0.09) at 3–6 months. Swallow function at 1 year was not clinically or statistically different between treatment methods. Conclusions: Modern radiotherapy achieves excellent functional outcomes in an unselected patient population, predominantly with advanced disease treated with CTRT. Omitting sub-site irradiation was associated with improved swallow recovery at 3–6 months but no difference persisted at one year. Longer follow up is required to characterise late swallow function post radiotherapy.