PURPOSE: In our Phase @entity263 Adaptive Radiation Therapy (ART) study, the highest possible dose was selected on the basis of normal tissue tolerance constraints. We analyzed @entity137 rates in different dose levels and treatment groups to determine whether equivalent @entity137 rates were achieved as hypothesized when the protocol was started. METHODS AND MATERIALS: From 1999 to 2002, 331 @entity1 with clinical stage T1 to T3, node-negative @entity263 were prospectively treated with three-dimensional conformal adaptive RT. A @entity1 -specific confidence-limited planning target volume was constructed on the basis of 5 CT scans and 4 sets of electronic portal images after the first 4 days of treatment. For each case, the rectum (rectal solid) was contoured in its entirety. The rectal wall was defined by use of a 3-mm wall thickness (median volume: 29.8 cc). The prescribed dose level was chosen using the following rectal wall dose constraints: (1) Less than 30% of the rectal wall volume can receive more than 75.6 Gy. (2) Less than 5% of the rectal wall can receive more than 82 Gy. Low-risk @entity1 (PSA < 10, Stage < or = T2a, Gleason score < 7) were treated to the prostate alone (Group 1). All other @entity1 , intermediate and high risk, where treated to the prostate and seminal vesicles (Group 2). The risk of chronic @entity137 (NCI Common @entity137 Criteria 2.0) was assessed for the different dose levels prescribed. HIC approval was acquired for all @entity1 . Median follow-up was 1.6 years. RESULTS: Grade 2 chronic @entity137 was experienced by 34 @entity1 (10%) (9% experienced @entity548 , 6% experienced @entity4272 , 3% experienced @entity294 , and 1% experienced @entity158 ) at a median interval of 1.1 year. Nine @entity1 (3%) experienced grade 3 or higher chronic @entity137 (1 Grade 4) at a median interval of 1.2 years. The 2-year rates of Grade 2 or higher and Grade 3 or higher chronic @entity137 were 17% and 3%, respectively. No significant difference by dose level was seen in the 2-year rate of Grade 2 or higher chronic @entity137 . These rates were 27%, 15%, 14%, 17%, and 24% for dose levels equal to or less than 72, 73.8, 75.6, 77.4, and 79.2 Gy, respectively (p = 0.3). Grade 2 or higher chronic @entity548 was significantly greater for Group 2 than for Group 1, 17% vs. 8% (p = 0.035). CONCLUSIONS: High doses (79.2 Gy) were safely delivered in selected @entity1 by our adaptive radiotherapy process. Under the rectal dose-volume histogram constraints for the dose level selection, the risk of chronic @entity137 is similar among @entity1 treated to different dose levels. Therefore, rectal chronic @entity137 rates reflect the dose-volume cutoff used and are independent of the actual dose levels. On the other hand, a larger @entity343 will increase the rectal wall dose and chronic @entity137 rates. @entity343 volume and dose constraints should be defined, considering their potential benefit.

Phase II dose escalation study of image-guided adaptive radiotherapy for XXXX : use of dose-volume constraints to achieve rectal isotoxicity.

@entity1 :: ('9606', 'Species') :: ['patients', 'patient'] @entity137 :: ('MESH:D064420', 'Disease') :: ['toxicity', 'Toxicity', 'rectal toxicity'] @entity263 :: ('MESH:D011471', 'Disease') :: ['II prostate cancer', 'prostate cancer'] @entity548 :: ('MESH:D006470', 'Disease') :: ['rectal bleeding'] @entity4272 :: ('MESH:D011349', 'Disease') :: ['proctitis'] @entity294 :: ('MESH:D003967', 'Disease') :: ['diarrhea'] @entity343 :: ('187978', 'Species') :: ['PTV'] @entity158 :: ('MESH:D010146', 'Disease') :: ['rectal pain']
@entity263 :: (MESH:D011471,Disease) :: ['prostate cancer']
