Table 2.
The numbers and mean XQ scores of patients who filled out the questionnaire at each time point by treatment group.
| Number of patients | Mean XQ scores | SD | ||||||
|---|---|---|---|---|---|---|---|---|
| Time intervals | IMRT | IMPT | IMRT | IMPT | D-value | IMRT | IMPT | P value |
| 0–3 months | 266 | 80 | 39.7 | 38.0 | +1.7 | 24.8 | 22.1 | 0.58 |
| 3–6 months | 130 | 41 | 36.6 | 36.5 | +0.1 | 23.8 | 22.8 | 1.00 |
| 6–9 months | 130 | 54 | 36.5 | 37.8 | −1.3 | 22.6 | 20.0 | 0.72 |
| 9–12 months | 88 | 42 | 30.8 | 27.9 | +2.9 | 23.0 | 18.6 | 0.48 |
| 12–18 months | 142 | 47 | 28.7 | 24.0 | +4.7 | 22.4 | 18.6 | 0.20 |
| 18–24 months | 138 | 53 | 29.0 | 22.4 | +6.6 | 22.4 | 16.8 | 0.051 |
| 24–36 months | 172 | 65 | 27.3 | 22.7 | +4.6 | 23.5 | 17.4 | 0.15 |
Abbreviations: IMRT, intensity-modulated (photon) radiation therapy; IMPT, intensity-modulated proton therapy; XQ, xerostomia questionnaire; D-value, difference value of mean XQ scores between IMRT and IMPT (IMRT-IMPT); SD, Standard deviation.