Role of principal component analysis in predicting XXXX in @entity263 @entity1 treated with hypofractionated intensity-modulated radiation therapy.

@entity1 @entity137 @entity263 @entity344
PURPOSE: To determine if principal component analysis (PCA) and standard parameters of rectal and bladder wall dose-volume histograms (DVHs) of @entity263 @entity1 treated with hypofractionated image-guided intensity-modulated radiotherapy (hypo-IMRT) can predict @entity344 . METHODS AND MATERIALS: One hundred twenty-one @entity1 underwent hypo-IMRT at 3 Gy/fraction, 5 days/week to either 60 Gy or 66 Gy, with daily online image guidance. @entity344 were recorded weekly during treatment and at each follow-up. All Radiation Therapy Oncology Group (RTOG) criteria @entity137 scores were dichotomized as <2 and >= 2. Standard dosimetric parameters and the first five to six principal components (PCs) of bladder and rectal wall DVHs were tested for association with the dichotomized @entity137 outcomes, using logistic regression. RESULTS: Median follow-up of all @entity1 was 47 months (60 Gy cohort = 52 months; 66 Gy cohort = 31 months). The incidence rates of >= 2 acute GI and GU @entity137 were 14% and 29%, respectively, with no Grade >= 3 acute GU @entity137 . Late GI and GU @entity137 scores >= 2 were 16% and 15%, respectively. There was a significant difference in late @entity344 >= 2 when comparing the 66 Gy to the 60 Gy cohort (38% vs. 8%, respectively, p = 0.0003). The first PC of the rectal DVH was associated with late @entity344 (odds ratio [OR], 6.91; p < 0.001), though it was not significantly stronger than standard DVH parameters such as Dmax (OR, 6.9; p < 0.001) or percentage of the organ receiving a 50% dose (V50) (OR, 5.95; p = 0 .001). CONCLUSIONS: Hypofractionated treatment with 60 Gy in 3 Gy fractions is well tolerated. There is a steep dose response curve between 60 Gy and 66 Gy for RTOG Grade >= 2 GI effects with the dose constraints employed. Although PCA can predict late @entity344 for @entity1 treated with hypo-IMRT for @entity263 , it provides no additional information over using more standard DVH parameters.
