Evaluation of rectal bleeding factors associated with prostate brachytherapy.
OBJECTIVE
To analyze rectal bleeding prognostic factors associated with prostate brachytherapy (PB) or in combination with external-beam radiation therapy (EBRT) and to examine dosimetric indications associated with rectal bleeding.


METHODS
The study included 296 patients followed up for >36 months (median, 48 months). PB was performed alone in 252 patients and in combination with EBRT in 44 patients. PB combined with EBRT is indicated for patients with a Gleason score >6. The prescribed dose was 144 Gy for monotherapy and 110 Gy for PB + EBRT (44-46 Gy).


RESULTS
Although 9.1% who received monotherapy had 2.3% grade 2 rectal bleeding, 36.3% who received combined therapy had 15.9% grade 2 rectal bleeding. Combined therapy was associated with higher incidence of rectal bleeding (P = 0.0049) and higher percentage of grade 2 bleeding (P = 0.0005). Multivariate analysis revealed that R-150 was the only significant factor for rectal bleeding, and modified Radiation Therapy Oncology Group (RTOG) grade in monotherapy and biologically equivalent dose (BED) were significant for combined therapy. Moreover, grade 2 rectal bleeding increased significantly at D90 > 130 Gy.


CONCLUSIONS
Although R-150 was the significant prognostic factor for rectal bleeding and modified RTOG rectal toxicity grade, BED was the significant prognostic factor for modified RTOG rectal toxicity grade.
Aoki
Manabu
M
Department of Radiology, Jikei University School of Medicine, Tokyo, Japan. maoki@jikei.ac.jp
Miki
Kenta
K
Sasaki
Hiroshi
H
Kido
Masato
M
Shirahama
Jun
J
Takagi
Sayako
S
Kobayashi
Masao
M
Honda
Chikara
C
Kanehira
Chihiro
C
D000368:Aged; D001918:Brachytherapy / Q000009:adverse effects*; D005500:Follow-Up Studies; D006471:Gastrointestinal Hemorrhage / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D015994:Incidence; D008297:Male; D015999:Multivariate Analysis; D011379:Prognosis; D011471:Prostatic Neoplasms / Q000453:epidemiology / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000009:adverse effects; D012002:Rectal Diseases / Q000453:epidemiology / Q000209:etiology*; D012189:Retrospective Studies; D012720:Severity of Illness Index; D013997:Time Factors; D014041:Tokyo / Q000453:epidemiology