Normal tissue complication probability (NTCP) models for late rectal bleeding, stool frequency and fecal incontinence after radiotherapy in prostate cancer patients

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• 作者：Wouter Schaake^a ; ^b ; ^{w.schaake@pl.hanze.nl" class="auth_mail" title="E-mail the corresponding author} ; Arjen van der Schaaf^a ; Lisanne V. van Dijk^a ; Alfons H.H. Bongaerts^c ; Alfons C.M. van den Bergh^a ; Johannes A. Langendijk^a
• 关键词：Side effects ; NTCP ; Prostate ; Toxicity ; Dose&ndash ; volume effects ; Prediction
• 刊名：Radiotherapy and Oncology
• 出版年：2016
• 出版时间：June 2016
• 年：2016
• 卷：119
• 期：3
• 页码：381-387
• 全文大小：993 K

文摘

Curative radiotherapy for prostate cancer may lead to anorectal side effects, including rectal bleeding, fecal incontinence, increased stool frequency and rectal pain. The main objective of this study was to develop multivariable NTCP models for these side effects.

Material and methods

The study sample was composed of 262 patients with localized or locally advanced prostate cancer (stage T1–3). Anorectal toxicity was prospectively assessed using a standardized follow-up program. Different anatomical subregions within and around the anorectum were delineated. A LASSO logistic regression analysis was used to analyze dose volume effects on toxicity.

Results

In the univariable analysis, rectal bleeding, increase in stool frequency and fecal incontinence were significantly associated with a large number of dosimetric parameters. The collinearity between these predictors was high (VIF > 5). In the multivariable model, rectal bleeding was associated with the anorectum (V70) and anticoagulant use, fecal incontinence was associated with the external sphincter (V15) and the iliococcygeal muscle (V55). Finally, increase in stool frequency was associated with the iliococcygeal muscle (V45) and the levator ani (V40). No significant associations were found for rectal pain.

Conclusions

Different anorectal side effects are associated with different anatomical substructures within and around the anorectum. The dosimetric variables associated with these side effects can be used to optimize radiotherapy treatment planning aiming at prevention of specific side effects and to estimate the benefit of new radiation technologies.