Genitourinary toxicity after high-dose-rate (HDR) brachytherapy combined with Hypofractionated External beam radiotherapy for localized prostate cancer: an analysis to determine the correlation between dose-volume histogram parameters in HDR brachytherapy and severity of toxicity.
OBJECTIVE
To evaluate the severity of genitourinary (GU) toxicity in high-dose-rate (HDR) brachytherapy combined with hypofractionated external beam radiotherapy (EBRT) for prostate cancer and to explore factors that might affect the severity of GU toxicity.


METHODS
A total of 100 Japanese men with prostate cancer underwent (192)Ir HDR brachytherapy combined with hypofractionated EBRT. Mean (SD) dose to 90% of the planning target volume was 6.3 (0.7) Gy per fraction of HDR. After 5 fractions of HDR treatment, EBRT with 10 fractions of 3 Gy was administrated. The urethral volume receiving 1-15 Gy per fraction in HDR brachytherapy (V1-V15) and the dose to at least 5-100% of urethral volume in HDR brachytherapy (D5-D100) were compared between patients with Grade 3 toxicity and those with Grade 0-2 toxicity. Prostate volume, patient age, and International Prostate Symptom Score were also compared between the two groups.


RESULTS
Of the 100 patients, 6 displayed Grade 3 acute GU toxicity, and 12 displayed Grade 3 late GU toxicity. Regarding acute GU toxicity, values of V1, V2, V3, and V4 were significantly higher in patients with Grade 3 toxicity than in those with Grade 0-2 toxicity. Regarding late GU toxicity, values of D70, D80, V12, and V13 were significantly higher in patients with Grade 3 toxicity than in those with Grade 0-2 toxicity.


CONCLUSIONS
The severity of GU toxicity in HDR brachytherapy combined with hypofractionated EBRT for prostate cancer was relatively high. The volume of prostatic urethra was associated with grade of acute GU toxicity, and urethral dose was associated with grade of late GU toxicity.
Ishiyama
Hiromichi
H
Department of Radiology, Kitasato University School of Medicine, Kitasato, Sagamihara, Kanagawa, Japan. hishiyam@kitasato-u.ac.jp
Kitano
Masashi
M
Satoh
Takefumi
T
Kotani
Shouko
S
Uemae
Mineko
M
Matsumoto
Kazumasa
K
Okusa
Hiroshi
H
Tabata
Ken-ichi
K
Baba
Shiro
S
Hayakawa
Kazushige
K
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000726:Androgen Antagonists / Q000627:therapeutic use; D001918:Brachytherapy / Q000009:adverse effects* / Q000379:methods; D005485:Flutamide / Q000627:therapeutic use; D006801:Humans; D007496:Iridium Radioisotopes / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology*; D011859:Radiography; D011878:Radiotherapy / Q000379:methods; D011879:Radiotherapy Dosage; D012007:Rectum / Q000000981:diagnostic imaging; D012044:Regression Analysis; D012062:Relative Biological Effectiveness; D047368:Tumor Burden; D014521:Urethra / Q000000981:diagnostic imaging / Q000528:radiation effects; D014566:Urogenital System / Q000528:radiation effects*
D000726:Androgen Antagonists; D007496:Iridium Radioisotopes; D005485:Flutamide