Dosimetric Predictors of Radiation-Induced Vaginal Stenosis After Pelvic Radiation Therapy for Rectal and XXXX .

@entity1 @entity137 @entity5 @entity1161 @entity850
PURPOSE: Although @entity850 ( @entity850 ) is a recognized @entity137 in @entity1 who receive pelvic @entity1161 ( @entity1161 ), the relationship between @entity1161 dose and the volume and extent of @entity137 has not been analyzed. We modeled this relationship to identify predictors of @entity850 . METHODS AND MATERIALS: We evaluated 54 @entity1 , aged 29 to 78 years, who underwent pelvic @entity1161 for @entity5 during 2008 to 2011 and were enrolled in a prospective study evaluating vaginal dilator use. Maximum dilator size was measured before @entity1161 (baseline) and 1 month and 12 months after @entity1161 . Dilator use was initiated at 1 month. The difference (D) in dilator size before and after @entity1161 was recorded. Those with D  <=-1 were classified as having @entity850 (n=35); those with D >= 0 were classified as having no @entity850 (n=19 at 1 month). Dose-volume parameters were extracted, and the generalized equivalent uniform dose (gEUD) was used to build a predictive model. RESULTS: The mean vaginal doses were 50.0 Gy and 36.8 Gy for anal and @entity5 @entity1 , respectively. One month after @entity1161 , a gEUD model using a wide range of a values suggests that sparing of vaginal volume to a low dose may be important. When gEUD (a = -1) was <35 Gy and the mean vaginal dose was <43 Gy, severe @entity850 was reduced (P=.02). A 1-year analysis suggests increasingly negative D values with increasing mean dose. However, @entity1 with compliance <40% were more likely to have @entity137 . CONCLUSIONS: Vaginal @entity850 is influenced by multiple @entity1161 dose-volume characteristics. Mean dose and gEUD constraints together may reduce the risk of severe @entity850 . @entity1 receiving higher mean vaginal doses should have greater compliance with dilator therapy to minimize risk of @entity137 . Further validation with independent datasets is needed.
