Prospective longitudinal study of patient-reported dysphagia in nasopharyngeal carcinoma treated with intensity-modulated proton therapy.

PURPOSE: To evaluate longitudinal changes in patient-reported dysphagia and identify its predictors in nasopharyngeal carcinoma (NPC) patients treated with intensity-modulated proton therapy (IMPT).

METHODS

Newly diagnosed, non-metastatic NPC patients were prospectively enrolled. The MD Anderson Dysphagia Inventory (MDADI) was administered at seven time points from baseline to 12 months post-IMPT. Primary endpoints included: (1) clinically significant decline (CSD), defined as a ≥10-point decrease in MDADI composite score from baseline to end of IMPT, and (2) no recovery to baseline (NRB) at 12 months. Clinical, sociodemographic, and dosimetric variables were analyzed.

RESULTS

Of 58 patients, 49 completed MDADI assessments at all time-points. CSD occurred in 69 %, and NRB in 34 %. Patients with CSD had significantly higher mean doses to the oral cavity and superior pharyngeal constrictor muscle (S-PCM) (p < 0.05), while those with NRB had higher doses to the oral cavity, S-PCM, and middle PCM (M-PCM) (p < 0.01). After adjustment clinical and sociodemographic variables, independent predictors of CSD were mean dose to oral cavity (OR = 1.210) and S-PCM (OR = 1.249). Predictors of NRB included mean dose to oral cavity (OR = 1.268), S-PCM (OR = 1.211), and M-PCM (OR = 1.166). Limiting mean doses below 12.2Gy[RBE] (oral cavity) and 55.4Gy[RBE] (S-PCM) reduced CSD risk to <0.6 and NRB risk to <0.2, respectively; a dose below 36.1 Gy[RBE] (M-PCM) reduced NRB risk to <0.2.

CONCLUSION

Minimizing mean doses to the oral cavity, S-PCM, and M-PCM is crucial for reducing patient-reported dysphagia following IMPT in NPC patients.