Carbon ion radiotherapy in advanced hypofractionated regimens for prostate cancer: from 20 to 16 fractions.
OBJECTIVE
To assess the effects of differences in dose fractionation on late radiation toxicity and biochemical control in patients with prostate cancer treated with carbon ion radiotherapy (C-ion RT).


METHODS
A total of 740 prostate cancer patients who received C-ion RT between April 2000 and February 2009 were analyzed. Of those, 664 patients followed for at least 1 year were analyzed with regard to late radiation toxicity. Biochemical relapse-free (BRF) and overall survival (OS) rates in patient subgroups with each dose-fractionation were analyzed.


RESULTS
Only 1 case of grade 3 genitourinary (GU) morbidity was observed in 20 fractions, and none of the patients developed higher grade morbidities. The incidence of late GU toxicity in patients treated with 16 fractions was lower than that of patients treated with 20 fractions. The OS rate and BRF rate of the entire group at 5 years were 95.2% and 89.7%, respectively. The 5-year BRF rate of the patients treated with 16 fractions of C-ion RT (88.5%) was comparable to that of the patients treated with 20 fractions (90.2%).


CONCLUSIONS
C-ion RT of 57.6 GyE (the physical C-ion dose [Gy]×RBE) in 16 fractions could offer an even lower incidence of genitourinary toxicity and comparable BRF rate than that in 20 fractions. Advancement in hypofractionation could be safely achieved with C-ion RT for prostate cancer.
National Institute of Radiological Sciences, Chiba, Japan.
Tohru
T
Okada
Hiroshi
H
Tsuji
Tadashi
T
Kamada
Koichiro
K
Akakura
Hiroyoshi
H
Suzuki
Jun
J
Shimazaki
Hirohiko
H
Tsujii
D000230:Adenocarcinoma / Q000097:blood / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D000368:Aged; D000369:Aged, 80 and over; D002244:Carbon / Q000009:adverse effects / Q000627:therapeutic use*; D019583:Dose Fractionation, Radiation; D063193:Heavy Ion Radiotherapy / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000473:pathology; D012007:Rectum / Q000528:radiation effects; D012189:Retrospective Studies; D015996:Survival Rate; D014566:Urogenital System / Q000528:radiation effects
D002244:Carbon; D017430:Prostate-Specific Antigen