Prospective Randomized study of intensity-modulated radiotherapy on salivary gland function in early-stage nasopharyngeal carcinoma patients

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.