Top Line: Does external beam radiation with a brachytherapy boost improve treatment outcomes compared to brachytherapy alone for intermediate risk prostate cancer?
The Study: When it comes to intermediate risk prostate cancer, there are mixed opinions about whether brachytherapy (BT) monotherapy is sufficient or if a base dose of external beam radiation (EBRT) is necessary to adequately treat subclinical disease around the prostate and seminal vesicles. RTOG 0232 was designed to answer this question. Eligible patients were cT1c-T2b and had either Gleason 6 disease and a PSA 10-20 (11%) or Gleason 7 disease and a PSA <10 (89%). Also, they had to have an AUA score <15 and a prostate volume ≤60cc. 579 patients were randomized to either BT monotherapy (145 Gy I-125 or 125 Gy Pd-103) or initial EBRT (45 Gy in 25 fractions to the prostate and seminal vesicles) followed by a BT boost (110 Gy I-125 or 100 Gy Pd-103). Fewer than 10% received ADT. At 5 years, there was no difference between the BT and EBRT+BT arms in freedom from progression (82.7% v 85.6%). Using the Phoenix definition, the rate of biochemical failure at 5 years was 8.1% with BT and 8.0% with EBRT+BT. The authors went back and assigned grade groups. Among GG2 patients, there was no difference in FFP between arms (85.3% v 89.4%) nor was there a difference for GG3 patients (77.3% v 77.0%). While acute toxicity was similar between arms, the rate of late grade 2+ GI/GU toxicity at 5 years was higher with EBRT+BT (42.8% v 25.8%) as was the rate of grade 3+ GI/GU toxicity (8.2% v 3.8%). Surprisingly, IMRT was associated with higher toxicity in the EBRT arm (although the trial was conducted between 2003 and 2012).
TBL: In RTOG 0232, the combination of external beam radiation with brachytherapy boost did not improve disease control but did increase late toxicity compared to brachytherapy alone in patients with intermediate risk prostate cancer. | Michalski, J Clin Oncol 2023
The Study: When it comes to intermediate risk prostate cancer, there are mixed opinions about whether brachytherapy (BT) monotherapy is sufficient or if a base dose of external beam radiation (EBRT) is necessary to adequately treat subclinical disease around the prostate and seminal vesicles. RTOG 0232 was designed to answer this question. Eligible patients were cT1c-T2b and had either Gleason 6 disease and a PSA 10-20 (11%) or Gleason 7 disease and a PSA <10 (89%). Also, they had to have an AUA score <15 and a prostate volume ≤60cc. 579 patients were randomized to either BT monotherapy (145 Gy I-125 or 125 Gy Pd-103) or initial EBRT (45 Gy in 25 fractions to the prostate and seminal vesicles) followed by a BT boost (110 Gy I-125 or 100 Gy Pd-103). Fewer than 10% received ADT. At 5 years, there was no difference between the BT and EBRT+BT arms in freedom from progression (82.7% v 85.6%). Using the Phoenix definition, the rate of biochemical failure at 5 years was 8.1% with BT and 8.0% with EBRT+BT. The authors went back and assigned grade groups. Among GG2 patients, there was no difference in FFP between arms (85.3% v 89.4%) nor was there a difference for GG3 patients (77.3% v 77.0%). While acute toxicity was similar between arms, the rate of late grade 2+ GI/GU toxicity at 5 years was higher with EBRT+BT (42.8% v 25.8%) as was the rate of grade 3+ GI/GU toxicity (8.2% v 3.8%). Surprisingly, IMRT was associated with higher toxicity in the EBRT arm (although the trial was conducted between 2003 and 2012).
TBL: In RTOG 0232, the combination of external beam radiation with brachytherapy boost did not improve disease control but did increase late toxicity compared to brachytherapy alone in patients with intermediate risk prostate cancer. | Michalski, J Clin Oncol 2023