Predictive Parameters of Symptomatic Hematochezia Following 5-Fraction Gantry-Based SABR in Prostate Cancer

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• 作者：Hima Bindu Musunuru ; MD ; FRCR(UK)^&lowast ; ; ^&dagger ; ; Melanie Davidson ; PhD^&lowast ; ; ^&Dagger ; ; Patrick Cheung ; MD ; FRCPC^&lowast ; ; ^&dagger ; ; Danny Vesprini ; MSc ; MD ; FRCPC^&lowast ; ; ^&dagger ; ; Stanley Liu ; MD ; PhD ; FRCPC^&lowast ; ; ^&dagger ; ; Hans Chung ; MD ; FRCPC^&lowast ; ; ^&dagger ; ; William Chu ; MD ; FRCPC^&lowast ; ; ^&dagger ; ; Alexandre Mamedov ; PhD^&lowast ; ; Ananth Ravi ; PhD^&lowast ; ; ^&Dagger ; ; Laura D'Alimonte ; BSc ; MHSc^&lowast ; ; ^&dagger ; ; Kristina Commisso ; BSc^&lowast ; ; Joelle Helou ; MD^&lowast ; ; ^&dagger ; ; Andrea Deabreu ; BSc^&lowast ; ; Liying Zhang ; PhD^§ ; ; Andrew Loblaw ; MD ; MSc ; FRCPC^&lowast ; ; ^&dagger ; ; ^‖ ; ^{andrew.loblaw@sunnybrook.ca" class="auth_mail" title="E-mail the corresponding author}
• 刊名：International Journal of Radiation Oncology*Biology*Physics
• 出版年：2016
• 出版时间：1 April 2016
• 年：2016
• 卷：94
• 期：5
• 页码：1043-1051
• 全文大小：540 K

文摘

This study identified predictors of high-grade late hematochezia (HH) following 5-fraction gantry-based stereotactic ablative radiation therapy (SABR).

Methods and Materials

Hematochezia data for 258 patients who received 35 to 40 Gy SABR in 5-fractions as part of sequential phase 2 prospective trials was retrieved. Grade 2 or higher late rectal bleeding was labeled HH. Hematochezia needing steroid suppositories, 4% formalin, or 1 to 2 sessions of argon plasma coagulation (APC) was labeled grade 2. More than 2 sessions of APC, blood transfusion, or a course of hyperbaric oxygen was grade 3 and development of visceral fistula, grade 4. Various dosimetric and clinical factors were analyzed using univariate and multivariate analyses. Receiver operating characteristic (ROC) curve analysis and recursive partitioning analysis were used to determine clinically valid cut-off points and identify risk groups, respectively.

Results

HH was observed in 19.4%, grade ≥3 toxicity in 3.1%. Median follow-up was 29.7 months (interquartile range [IQR]: 20.6-61.7) Median time to develop HH was 11.7 months (IQR: 9.0-15.2) from the start of radiation. At 2 years, cumulative HH was 4.9%, 27.2%, and 42.1% in patients who received 35 Gy to prostate (4-mm planning target volume [PTV] margin), 40 Gy to prostate (5-mm PTV margin), and 40 Gy to prostate/seminal vesicles (5-mm PTV margin), respectively (P<.0001). In the ROC analysis, volume of rectum receiving radiation dose of 38 Gy (V38) was a strong predictor of HH with an area under the curve of 0.65. In multivariate analysis, rectal V38 (≥2.0 cm³; odds ratio [OR]: 4.7); use of anticoagulants in the follow-up period (OR: 6.5) and presence of hemorrhoids (OR: 2.7) were the strongest predictors. Recursive partitioning analysis showed rectal V38 < 2.0 cm³, and use of anticoagulants or rectal V38 ≥ 2.0 cm³ plus 1 other risk factor resulted in an HH risk of >30%.

Conclusions

Rectal V38 and 2 clinical factors were strong predictors of HH following 5-fraction SABR. Planning constraints should keep rectal V38 below 2.0 cm³.