Risk factors of late rectal bleeding after carbon ion therapy for prostate cancer.
OBJECTIVE
The aim of this study was to determine the risk factors for late gastrointestinal (GI) morbidity after hypofractionated carbon ion radiotherapy (C-ion RT) for prostate cancer.


METHODS
Between April 2000 and November 2003, a Phase II clinical trial of C-ion RT with a total dose of 66 GyE in 20 fractions was performed on 175 patients with prostate cancer, and the correlations of clinical and dosimetric parameters with the incidence of late GI toxicity in 172 patients who survived for more than 18 months were investigated.


RESULTS
Although no Grade 3-4 late morbidities of the rectum were observed, Grade 1 and 2 morbidities developed in 23 (13%) and 4 (2%) patients, respectively. Dose-volume histogram analysis revealed that the percentage of rectal volume receiving 50% of the prescribed dose (V50) was significantly higher in patients with rectal toxicity than without toxicity (13.2 +/- 5.6% with toxicity; 11.4 +/- 4.0% without toxicity, p = 0.046). Multivariate analysis demonstrated that the use of anticoagulation therapy (p = 0.010) and rectal V50 (p = 0.012) were significant risk factors for the occurrence of Grade 1-2 late GI toxicity.


CONCLUSIONS
Although C-ion RT with hypofractionation yielded favorable results regarding late GI complication, dosimetric parameter was a very important factor in the occurrence of rectal bleeding after C-ion RT as well as photon beam RT. Our results provide useful information for physicians applying charged particle RT in the treatment of prostate cancer.
Ishikawa
Hitoshi
H
Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba, Japan.
Tsuji
Hiroshi
H
Kamada
Tadashi
T
Hirasawa
Naoki
N
Yanagi
Takeshi
T
Mizoe
Jun-Etsu
JE
Akakura
Koichiro
K
Suzuki
Hiroyoshi
H
Shimazaki
Jun
J
Tsujii
Hirohiko
H
D000368:Aged; D000369:Aged, 80 and over; D002250:Carbon Radioisotopes / Q000009:adverse effects*; D015897:Comorbidity; D006471:Gastrointestinal Hemorrhage / Q000401:mortality*; D020450:Heavy Ions / Q000009:adverse effects*; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011471:Prostatic Neoplasms / Q000401:mortality* / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000453:epidemiology*; D012002:Rectal Diseases / Q000401:mortality*; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D016019:Survival Analysis; D015996:Survival Rate
D002250:Carbon Radioisotopes