Correlation between dosimetric parameters and late rectal and urinary toxicities in patients treated with high-dose-rate brachytherapy used as monotherapy for prostate cancer.
OBJECTIVE
To evaluate the correlation between dosimetric parameters and late rectal and urinary toxicities in high-dose-rate brachytherapy (HDR-BT) used as monotherapy for prostate cancer.


METHODS
The data of 83 patients treated with HDR-BT alone for prostate cancer from 2001 through 2005 at Osaka University Hospital were analyzed. Median follow-up time was 36 months (range, 18-70). The total prescribed dose was 54 Gy in nine fractions over 5 days. Correlation between dosimetric parameters and late toxicities was examined.


RESULTS
The means of V30, V40, V50, V60, V70, D1cc, D2cc, D5cc, and D10cc of the rectum were significantly higher in 18 patients who presented with late rectal toxicity (Grades 1-3 rectal bleeding) than in the other 65 patients who did not. A significant difference was observed for D1cc-10cc but not for D5-90. The statistically most significant difference was observed for V40 and D5cc. Late rectal toxicity rate was significantly higher for patients with rectal V40 >or= 8 cc than those with the rectal V40 < 8 cc (42% vs. 8%; p < 0.001), as well as for patients with rectal D5cc >or= 27 Gy compared with those with rectal D5cc < 27 Gy (50% vs. 11%; p < 0.001). Dosimetric parameters of the urethra of 15 patients with late urinary toxicity were not significantly different from the 68 patients without toxicity.


CONCLUSIONS
Rectal V40 < 8 cc and D5cc < 27 Gy may be dose-volume constraints in HDR-BT used as monotherapy for prostate cancer.
Konishi
Koji
K
Department of Radiation Oncology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
Yoshioka
Yasuo
Y
Isohashi
Fumiaki
F
Sumida
Iori
I
Kawaguchi
Yoshifumi
Y
Kotsuma
Tadayuki
T
Adachi
Kana
K
Morimoto
Masahiro
M
Fukuda
Shoichi
S
Inoue
Takehiro
T
D000230:Adenocarcinoma / Q000473:pathology / Q000532:radiotherapy*; D000368:Aged; D000726:Androgen Antagonists; D001918:Brachytherapy / Q000009:adverse effects* / Q000379:methods; D005500:Follow-Up Studies; D006471:Gastrointestinal Hemorrhage / Q000209:etiology; D006417:Hematuria / Q000209:etiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000150:complications*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012007:Rectum / Q000528:radiation effects*; D047368:Tumor Burden / Q000528:radiation effects; D014521:Urethra / Q000528:radiation effects*; D014555:Urination Disorders / Q000209:etiology
D000726:Androgen Antagonists; D017430:Prostate-Specific Antigen