Table 6. Parameter estimates from the univariate logistic regression NTCP model.
| HNSCC | NPC | ||||
|---|---|---|---|---|---|
| Month | Parameter | TD50 (CI95%) | γ (CI95%) | TD50 (CI95%) | γ (CI95%) |
| 3m | Dmean-c | 24.3 (24.0–24.5) | 8.30 (7.25–9.44) | 36.0 (34.3–37.8) | 1.69 (1.64–1.71) |
| Dmean-i | 35.3 (33.3–37.4) | 1.80 (1.80–1.83) | 38.3 (36.1–40.7) | 1.39 (1.33–1.44) | |
| 12m | Dmean-c | 25.4 (24.5–26.3) | 2.41 (2.20–2.54) | 40.0 (39.1–40.9) | 3.96 (3.56–3.99) |
| Dmean-i | 38.0 (34.9–41.2) | 1.17 (1.17–1.21) | 42.8 (41.9–43.7) | 4.35 (3.92–4.30) | |
Abbreviation: NTCP: Normal tissue complication probability; HNSCC: head and neck squamous cell carcinoma; NPC: nasopharyngeal carcinoma; TD50: the gland tolerance dose (Gy) that would result in a 50% risk of normal tissue complications for patient-reported moderate- to-severe xerostomia within a specific period of time; γ: the slope of the response curve. Dmean-c: mean dose to the contralateral parotid glands; Dmean-i: mean dose to the ipsilateral parotid glands.