Purpose: To determine the relationship between quality of life (QOL) and xerostomia over time for patients undergoing radiotherapy (RT) for head-and-neck cancer in a prospective clinical trial.
Methods and materials: Patients with head-and-neck cancer were randomized to pilocarpine (n = 65) vs. placebo (n = 65) during RT. QOL was measured using the McMaster Head and Neck Radiotherapy Questionnaire (HNRQ). Xerostomia was measured on a linear analog scale. No statistically significant differences were observed between arms; all 130 patients were analyzed together.
Results: Baseline QOL data were obtained for 98.5% of participants. The baseline HNRQ score of 5.7 declined significantly to 4.0 (p <0.0001) by RT Week 6 and returned to baseline (5.8) by 6 months after treatment. This represents a large, clinically important change of 1.7 of 7 (24%; effect size 1.34). The decline in HNRQ score during RT paralleled the onset of xerostomia on the linear analog scale (r = 0.36 at 1 month). After treatment, the QOL scores recovered without improvement in xerostomia. The trajectory of the linear analog scale score resembled that of the HNRQ's single xerostomia question (r = 0.75 at 1 month).
Conclusion: Quality of life recovers to baseline after RT, despite persistent xerostomia. Either a response shift occurs or xerostomia in the absence of acute mucositis has a relatively small influence on overall QOL.