Comparison of common terminology criteria for adverse events v3.0 and radiation therapy oncology group toxicity score system after high-dose-rate interstitial brachytherapy as monotherapy for prostate cancer.

AIM The evaluation of toxicity after high-dose-rate interstitial brachytherapy (HDR-ISBT) as monotherapy for localized prostate cancer. MATERIALS AND METHODS We analyzed early and late toxicities in 100 patients treated by HDR-ISBT as monotherapy at the National Hospital Organization Osaka National Hospital using both Common Terminology Criteria for Adverse Events version 3.0 (CTCAE v3.0) and Radiation Therapy Oncology Group (RTOG) score. The median follow-up was 72 (range=12-109) months. RESULTS Late-gastrointestinal (GI) toxicities were 4% grade 1 and 2% grade 2 in CTCAE v3.0 and 5% grade 1 in RTOG score. Late genitourinary (GU) toxicities grade 1: grade 2: grade 3 were 29%: 5%: 2% in RTOG and 47%: 10%: 2% in CTCAE v3.0. CTCAE v3.0 GU score identified more grade 1-2 adverse reactions than the RTOG score (p=0.01). Early RTOG GI toxicity-positive patients showed 13% of late RTOG GI toxicity, whereas early RTOG GI negative patients showed 0% of RTOG (p=0.0172) and CTCAE v3.0 late-GI toxicity (p=0.007). CONCLUSION CTCAE v3.0 GU score identified more grade 1-2 adverse reactions than the RTOG score. Early RTOG GI toxicity is well-correlated to late GI toxicity and absence of RTOG acute GI toxicity is a safe surrogate for late GI toxicity after HDR-ISBT as monotherapy for prostate cancer.