• Tetsuo Akimoto, Hiroyuki Katoh, Yoshizumi Kitamoto, Tomoaki Tamaki, Kosaku Harada, Katsuyuki Shirai, and Takashi Nakano.
• Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
• Int. J. Radiat. Oncol. Biol. Phys. 2006 Jun 1; 65 (2): 364-70.

PurposeTo evaluate the incidence of Grade 2 or worse rectal bleeding after high-dose-rate (HDR) brachytherapy combined with hypofractionated external-beam radiotherapy (EBRT), with special emphasis on the relationship between the incidence of rectal bleeding and the rectal dose from HDR brachytherapy.Methods And MaterialsThe records of 100 patients who were treated by HDR brachytherapy combined with EBRT for > or =12 months were analyzed. The fractionation schema for HDR brachytherapy was prospectively changed, and the total radiation dose for EBRT was fixed at 51 Gy. The distribution of the fractionation schema used in the patients was as follows: 5 Gy x 5 in 13 patients; 7 Gy x 3 in 19 patients; and 9 Gy x 2 in 68 patients.ResultsTen patients (10%) developed Grade 2 or worse rectal bleeding. Regarding the correlation with dosimetric factors, no significant differences were found in the average percentage of the entire rectal volume receiving 30%, 50%, 80%, and 90% of the prescribed radiation dose from EBRT between those with bleeding and those without. The average percentage of the entire rectal volume receiving 10%, 30%, 50%, 80%, and 90% of the prescribed radiation dose from HDR brachytherapy in those who developed rectal bleeding was 77.9%, 28.6%, 9.0%, 1.5%, and 0.3%, respectively, and was 69.2%, 22.2%, 6.6%, 0.9%, and 0.4%, respectively, in those without bleeding. The differences in the percentages of the entire rectal volume receiving 10%, 30%, and 50% between those with and without bleeding were statistically significant.ConclusionsThe rectal dose from HDR brachytherapy for patients with prostate cancer may have a significant impact on the incidence of Grade 2 or worse rectal bleeding.

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