Treatment outcomes and late toxicities of intensity-modulated radiation therapy for 1091 Japanese patients with localized prostate cancer

Abstract

Aim

This study aimed to evaluate the treatment result of intensity-modulated radiation therapy (IMRT) in a large number of Japanese patients with prostate cancer.

Background

A total of 1091 patients with localized prostate cancer were recruited between March 2006 and July 2014. The patients were stratified into low- (n[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]205 [18.8%]), intermediate- (n[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]450 [41.2%]), high- (n[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]345 [31.6%]), and very high-risk (n[[ce:hsp sp="0.25"/]]=[[ce:hsp sp="0.25"/]]91 [8.3%]) groups according to the National Comprehensive Cancer Network classification. All patients were irradiated via IMRT at a dose of 74–78[[ce:hsp sp="0.25"/]]Gy with or without androgen-deprivation therapy. The mean follow-up period was 50 months (range, 2–120 months).

Results

The biochemical failure-free rate (BFFR), the clinical failure-free rate, and the overall survival rate at the 5-year follow-up for all patients was 91.3%, 96.2%, and 99.1%, respectively. In univariate analysis, the prostate-specific antigen (PSA) levels (≤20 vs. >20[[ce:hsp sp="0.25"/]]ng/ml) were significantly correlated with BFFR. A trend toward higher BFFR was noted in patients with a Gleason score (GS) of ≤7 than in patients with GS ≥8. In multivariate analysis, only PSA (≤20 vs. >20[[ce:hsp sp="0.25"/]]ng/ml) was significantly correlated with BFFR. The cumulative incidence rate of gastrointestinal and genitourinary toxicity (≥grade 2) at the 5-year follow-up was 11.4% and 4.3%, respectively.

Conclusions

The findings of this study indicate that IMRT is well tolerated and is associated with both good long-term tumor control and excellent outcomes in patients with localized prostate cancer.