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document
The benefits of including clinical factors in rectal normal tissue complication probability modeling after radiotherapy for prostate cancer . PURPOSE To study the impact of clinical predisposing factors on rectal normal tissue complication probability modeling using the updated results of the Dutch prostate dose-escalation trial . METHODS AND MATERIALS Toxicity data of 512 patients ( conformally treated to 68 Gy [ n = 284 ] and 78 Gy [ n = 228 ] ) with complete follow-up at 3 years after radiotherapy were studied . Scored end points were rectal bleeding , high stool frequency , and fecal incontinence . Two traditional dose-based models ( Lyman-Kutcher-Burman ( LKB ) and Relative Seriality ( RS ) and a logistic model were fitted using a maximum likelihood approach . Furthermore , these model fits were improved by including the most significant clinical factors . The area under the receiver operating characteristic curve ( AUC ) was used to compare the discriminating ability of all fits . RESULTS Including clinical factors significantly increased the predictive power of the models for all end points . In the optimal LKB , RS , and logistic models for rectal bleeding and fecal incontinence , the first significant ( p = 0.011-0.013 ) clinical factor was " previous abdominal surgery . " As second significant ( p = 0.012-0.016 ) factor , " cardiac history " was included in all three rectal bleeding fits , whereas including " diabetes " was significant ( p = 0.039-0.048 ) in fecal incontinence modeling but only in the LKB and logistic models . High stool frequency fits only benefitted significantly ( p = 0.003-0.006 ) from the inclusion of the baseline toxicity score . For all models rectal bleeding fits had the highest AUC ( 0.77 ) where it was 0.63 and 0.68 for high stool frequency and fecal incontinence , respectively . LKB and logistic model fits resulted in similar values for the volume parameter . The steepness parameter was somewhat higher in the logistic model , also resulting in a slightly lower D ( 50 ) . Anal wall DVHs were used for fecal incontinence , whereas anorectal wall dose best described the other two endpoints . CONCLUSIONS Comparable prediction models were obtained with LKB , RS , and logistic NTCP models . Including clinical factors improved the predictive power of all models significantly .
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Intervention_Other
complication probability modeling
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Intervention_Physical
radiotherapy
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Intervention_Other
Two traditional dose-based models ( Lyman-Kutcher-Burman ( LKB ) and Relative Seriality ( RS ) and a logistic model
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Outcome_Physical
High stool frequency
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Participant_Condition
after radiotherapy
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Participant_Condition
prostate cancer
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Participant_Sample-size
512
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Participant_Sample-size
284
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Participant_Sample-size
228