Radiotherapy for Hypopharyngeal Carcinoma: Analysis of Multi-institutional Data From Over 170 Patients.

Aim To examine the efficacy of radiotherapy (RT) for treating hypopharyngeal carcinoma (HPC), including the impact of transitioning from conventional three-dimensional conformal radiotherapy (3DCRT) to intensity-modulated radiotherapy (IMRT). Materials and methods We examined the outcomes of 171 patients with Stage I-IV HPC who were treated with definitive RT (87 with 3DCRT and 84 with IMRT) at three institutions between 2008 and 2024. The primary endpoint was overall survival (OS), and the secondary endpoints were local control (LC), locoregional control (LRC), progression-free survival (PFS), and toxicity. Results With a median follow-up time of 32 months (range, 2-127 months), the 2-year (2y) and 5-year (5y) OS rates were 83.9% (95% confidence interval [CI]: 77.1-88.9%) and 69.0% (95% CI: 58.8-77.1%), respectively. The 2y LC (5y), LRC, and PFS were 81.1% (74.1%), 78.1% (71.3%), and 64.3% (52.3%), respectively. The advanced T category was a statistically significant predictor of poor prognosis for both LC and LRC in the univariate analysis. Multivariate analyses found that N category (N0-1 vs. N2-3, hazard ratio = 1.7, 95% CI: 1.16-2.5, P = 0.0068) was a statistically significant predictor of OS. Five patients (2.8%) experienced late toxicities of grade ≥ 3. The transition from conventional 3DCRT to IMRT did not significantly alter the tumor control or toxicity profiles. Conclusion Definitive RT achieved favorable OS, LC, LRC, and PFS in patients with HPC, with acceptable toxicity. IMRT provides comparable efficacy and safety to 3DCRT for the treatment of HPC.