Dose-volume response in acute dysphagia toxicity: Validating QUANTEC recommendations into clinical practice for head and neck radiotherapy.

Purpose: To determine the validity of QUANTEC recommendations in predicting acute dysphagia using intensity-modulated head and neck radiotherapy.

Material And Methods: Seventy-six consecutive patients with locally advanced squamous cell carcinoma (SCC) of the head and neck +/- systemic therapy were analyzed. Multiple dose parameters for the larynx (V50Gy, Dmean and Dmax) were recorded. Acute dysphagia toxicity was prospectively scored in all treatment weeks (week 1-6 or 1-7) using CTCAEv3 by three blinded investigators. QUANTEC larynx recommendations (V50Gy < 27%, Dmean < 44 Gy, Dmean < 40 Gy, Dmax < 66 Gy) were used to group the cohort (i.e. V50Gy < 27% vs. V50Gy > 27%). The proportion of patients with Grade 3 dysphagia was compared within each group.

Results: There was a significant reduction in the incidence of grade 3 toxicity in the V50Gy < or > 27% group at week 5 (14.3% vs. 45.2%, p = 0.01) and 6 (25.9% vs. 65.9%, p < 0.01). A significant reduction at week 5 (14.7% vs. 50.0, p = 0.02) and 6 (32.4% vs. 67.6%, p = 0.01) was seen in Dmean < 44 Gy when compared to Dmean > 44 Gy. Dmean < 40 Gy also delivered a significant reduction at week 5 (5.6% vs. 42.3%, p < 0.01) and week 6 (23.5% vs. 59.3%, p = 0.01). A significant toxicity reduction at treatment week 6 (28.0% vs. 63.0%, p = 0 < 01) was seen from Dmax < 66 Gy to Dmax > 66 Gy. V50Gy > 27% (p < 0.01), Dmean > 40 Gy (p = 0.01) and Dmax > 66 Gy (p < 0.01) were also predictors of Grade 3 dysphagia when analyzed with multiple clinical risk factors.

Conclusions: QUANTEC late toxicity recommendations for dose to larynx during IMRT are a useful predictor for acute dysphagia toxicity in this patient cohort. Furthermore, this included chemoradiotherapy regimes and post-operative radiotherapy patients, allowing for prophylactic implementation of supportive care measures.