(H&L test, p=0.55) and calibration plot (slope:1.02,. R2=0.92). In Figure, the risk of 3-year INC vs EQD2 (alpha- beta=0.8Gy) is shown with the calibration plot of ...
(H&L test, p=0.55) and calibration plot (slope:1.02, R2=0.92). In Figure, the risk of 3-year INC vs EQD2 (alphabeta=0.8Gy) is shown with the calibration plot of the final two-variable model. The validity of the model was confirmed in the HYPO subgroup. Conclusion The incidence of patient-reported 3-year INC after highdose RT for prostate cancer dramatically depends on the prescribed dose (EQD2) and, secondarily, on the age of patients. A previously suggested low alpha-beta value (0.8Gy) for late INC resulted in a significantly better calibrated model, consistently with a high sensitivity of late I NC to fractionation.
(iMM) and the ipsilateral medial pterygoid muscle (iMPM). It is unclear whether these muscles should be regarded as a joined Organ at Risk or separately. The aim of our study was to calculate and compare separate dose-effect relationships between trismus and 1) the dose to the iMM and 2) iMPM dose, taking into account the baseline MMO. Material and Methods For 83 patients, participating in an exercise program to preserve oral function in the period 2008 - 2014, pre- and post-RT (6 weeks) MMO measurements were available. Treated tumors were mainly located in the oropharynx (40%) and hypopharynx (31%). All patients received concomitant radiotherapy (35x2Gy) via IMRT or VMAT technique with cisplatin 100mg/m2 at day 1,22 and 43. Pathological MMO (trismus) was set at ≤35mm as a functional cut-off. Exclusion criteria were trismus at baseline and gross tumor infiltration of the iMM or iMPM on planning CT. The muscles were retrospectively delineated. A logistic regression with bootstrapping resampling technique (n=2000) was applied to calculate model parameters. Dose-volume parameters (mean-, absolute- and relative dose) were calculated in 5 Gy steps. Results MMO showed a large range (Fig A) with 14 trismus cases (17%) post-RT. Baseline MMO was a significant predictor for trismus (p=0.005) with an optimal cutoff at 45mm. Women more often had a baseline MMO ≤ 45 (65%) compared to men (37%, p=0.02) and therefore had a higher trismus risk (30% vs 12%, p=0.04). Mean doses of the iMPM and iMM correlated significantly (Fig B, Pearson coefficient 0.83, p
