Prospective Randomized Study of Intensity-Modulated Radiotherapy on Salivary Gland Function in Early-Stage Nasopharyngeal Carcinoma Patients

TLDR

The study compared delayed xerostomia rates between two‑dimensional radiation therapy and intensity‑modulated radiation therapy in early‑stage nasopharyngeal carcinoma patients. Sixty T1‑2bN0‑1M0 NPC patients were randomized to IMRT or 2DRT, with the primary endpoint being observer‑rated severe xerostomia at one year and secondary assessments of patient‑reported outcomes and stimulated salivary flow rates. At one year, IMRT reduced severe xerostomia incidence to 39.3% versus 82.1% with 2DRT, improved stimulated parotid and whole‑saliva flow rates, but patient‑reported xerostomia showed no significant difference, highlighting the need to protect additional salivary glands.

Abstract

Purpose This randomized trial compared the rates of delayed xerostomia between two-dimensional radiation therapy (2DRT) and intensity-modulated radiation therapy (IMRT) in the treatment of early-stage nasopharyngeal carcinoma (NPC). Patients and Methods Between November 2001 and December 2003, 60 patients with T1-2bN0-1M0 NPC were randomly assigned to receive either IMRT or 2DRT. Primary end point was incidence of observer-rated severe xerostomia at 1 year after treatment based on Radiotherapy Oncology Group /European Organisation for the Research and Treatment of Cancer late radiation morbidity scoring criteria. Parallel assessment with patient-reported outcome, stimulated parotid flow rate (SPFR), and stimulated whole saliva flow rate (SWSFR) were also made. Results At 1 year after treatment, patients in IMRT arm had lower incidence of observer-rated severe xerostomia than patients in the 2DRT arm (39.3% v 82.1%; P = .001), parallel with a higher fractional SPFR (0.90 v 0.05; P < .0001), and higher fractional SWSFR (0.41 v 0.20; P = .001). As for patient's subjective feeling, although a trend of improvement in patient-reported outcome was observed after IMRT, recovery was incomplete and there was no significant difference in patient-reported outcome between the two arms. Conclusion IMRT is superior to 2DRT in preserving parotid function and results in less severe delayed xerostomia in the treatment of early-stage NPC. Incomplete improvement in patient's subjective xerostomia with parotid-sparing IMRT reflects the need to enhance protection of other salivary glands.