Matched case-control study of quality of life and xerostomia after intensity-modulated radiotherapy or standard radiotherapy for head-and-neck cancer: Initial report

Purpose: To compare quality of life (QOL) and xerostomia between head-and-neck cancer patients who received standard radiotherapy (RT) and patients matched by factors known to affect QOL who received intensity-modulated RT (IMRT). Methods and Materials: This was a prospective, longitudinal study of patients with head-and-neck cancer requiring bilateral neck irradiation who received IMRT at the University of Michigan and patients who received standard RT at affiliated clinics. Each patient received a validated head-and-neck cancer-related QOL questionnaire (HNQOL) consisting of four multi-item domains - Eating, Communication, Pain, and Emotion - and a validated patient-reported xerostomia questionnaire (XQ). In both questionnaires, the answers were scored 0-100, with higher scores denoting worse QOL or xerostomia. The questionnaires were given before therapy and at 1, 3, 6, 12, 18, and 24 months after the completion of therapy. Each standard RT patient was matched with several IMRT patients according to tumor site, stage, RT status (postoperative or definitive), and age. A linear mixed-effects model was fit to compare outcomes between the two treatment groups and to model trends over time. To account for matching, the differences in scores between the matched sets of patients were fit as a random intercept. Also, matching was taken into account in the model by using the standard error of the within-paired-groups differences. Results: Between 1997 and 2002, 10 patients who had received standard RT and answered the XQ and HNQOL through at least 1 year were included in the study. Each of these patients was matched with a subgroup of 2-5 patients (median, 3) who had received IMRT, had similar patient and tumor characteristics, and answered the same questionnaires. A total of 30 patients were included in the IMRT group. During the initial months after therapy, the XQ and HNQOL summary scores worsened significantly in both groups compared with the pretherapy scores. Starting at 6 months, improvements of both XQ and HNQOL scores were found over time in the IMRT patients (p = 0.01 and 0.04, respectively), compared with no trend of improvement in the standard RT patients (p = 0.5 and 0.9, respectively). The trend of improvement over time in QOL in the IMRT patients was noted in most of the HNQOL domains (Eating: p = 0.07, Pain: p = 0.05, Emotion: p = 0.04, and Communication: p = 0.13), compared with no trend of improvement in most of the domains in the standard RT patients. As the scores of the IMRT (but not the standard RT) patients improved over time, the differences between the groups in the mean XQ and HNQOL summary scores widened. At 12 months, median XQ and HNQOL scores were lower (better) in the IMRT compared with the standard RT patients by 19 and 20 points, respectively, adjusted for the pretherapy values (p = 0.2). In both groups, the pretherapy XQ and HNQOL summary scores were significantly related to the respective posttherapy scores (p = 0.02 and p < 0.01, respectively). Conclusions: After initial posttherapy declines in both groups, xerostomia and QOL improved over time after IMRT but not after standard RT. The potential benefits gained from IMRT in xerostomia or in QOL, compared with standard RT, are best reflected late (<6 months) after therapy.