Predictive Factors For Late Rectal Bleeding After External Radiotherapy For Prostate Cancer

Intractable late rectal bleeding toxicity is considered a serious complication of radiotherapy (RT) for localized prostate cancer (PC). We retrospectively assessed factors correlated with late rectal bleeding (LRB) in for PC patients who underwent definitive external (EX) RT. We analyzed the clinical records of 246 patients with Stage T1c-T4 PC treated using three-dimensional conformal radiotherapy (3D-CRT) or intensity-modulated RT (IMRT) at Tohoku University Hospital between June 2000 and May 2007. Median patient age was 71 years (range, 50-83 years). Patients were classified according to prognostic factors (Gleason score, pretreatment PSA level and clinical stage) as low (n = 10), intermediate (n = 82) or high (n = 154) risk. All patients received EXRT (median, 76 Gy; range, 70-80 Gy). No patients received prostatectomy or seed implant, while 189 pts received neoadjuvant, concurrent or adjuvant hormonal therapy (HT). Anticoagulants/antiaggregants were used by 47 patients because of cerebrovascular or cardiovascular disease. LRB was assessed according to the Radiation Therapy Oncology Group late radiation morbidity scoring scale. The following factors were investigated in association with LRB of Grade 2 or worse: age; T stage; pretreatment PSA level; Gleason score; risk classification; total irradiated dose; RT modality (3D-CRT or IMRT); administration of HT; presence of double cancer; and medication of anticoagulants/antiaggregants. The 5-year actuarial incidence of LRB was assessed using Kaplan-Meier survival analysis. In univariate analysis, log-rank test and Mann-Whitney tests were performed. Multivariate analysis was performed using the Cox regression model. Median follow-up was 19 months (range, 6-72 months). Grade 2 LRB was seen in 8 patients, while 2 patients had Grade 3 LRB and needed a single coagulation procedure. No patients had LRB of Grade 4. At 5 years, cumulative incidence of LRB of Grade 2 or worse was 8.2%. In univariate analysis, use of anticoagulants/antiaggregants (p = 0.013) and stage T4 (p = 0.0088) correlated with LRB of Grade 2 or worse. However, age (p = 0.74), presence of double cancer (p = 0.16), pretreatment PSA level (p = 0.88), Gleason score (p = 0.28), risk classification (p = 0.52), HT (p = 0.70), total irradiated dose (p = 0.96) and RT modality (p = 0.82) showed no significant relationship to LRB of Grade 2 or worse. Multivariate analysis identified the use of anticoagulant/antiaggregants (p = 0.02) and stage T4 (p = 0.005) as significantly associated with LRB of Grade 2 or worse. The present results demonstrate that the use of anticoagulants/antiaggregants and stage T4 appear to be highly predictive for LRB of Grade 2 or worse after curative EXRT for PC.