Top Line: What are long-term disease control outcomes for prostate SBRT with MRI-guided simultaneous integrated boost?
The Study: We’ve seen a number of trials recently exploring different ways to dose-escalate intraprostatic disease when delivering prostate SBRT. One approach has been to deliver a relatively standard dose to the entire prostate while simultaneously boosting (SIB) MRI-defined gross disease. The goal with this approach is to dose-escalate a smaller volume of clinically significant disease while giving a lower dose to a larger volume to hopefully reduce the risk of toxicity. Here are 5-year outcomes from a small prospective trial of prostate SBRT with SIB. Twenty six patients with low (23%) or intermediate (77%) risk disease had MRI and placement of gold fiducials. Two CTVs were delineated(entire prostate and MRI-defined gross disease) and both were expanded by 5mm (3mm posterior). The prostate PTV received 36.25 Gy in 5 fractions and the SIB PTV received 40 Gy. After a median >50 months median follow up, there were no biochemical or clinical recurrences. Median post-treatment PSA was 0.23. There were also no grade 3 toxicity events. The rate of late CTCAE grade 2 GU toxicity was 38.5%, and the rate of late grade 2 GI toxicity was 11.5%.
TBL: This small trial demonstrated excellent long-term disease control when treating the entire prostate to 36.25 Gy in 5 fractions with a 40 Gy SIB to MRI-defined disease. | Maas, Pract Radiat Oncol 2023
The Study: We’ve seen a number of trials recently exploring different ways to dose-escalate intraprostatic disease when delivering prostate SBRT. One approach has been to deliver a relatively standard dose to the entire prostate while simultaneously boosting (SIB) MRI-defined gross disease. The goal with this approach is to dose-escalate a smaller volume of clinically significant disease while giving a lower dose to a larger volume to hopefully reduce the risk of toxicity. Here are 5-year outcomes from a small prospective trial of prostate SBRT with SIB. Twenty six patients with low (23%) or intermediate (77%) risk disease had MRI and placement of gold fiducials. Two CTVs were delineated(entire prostate and MRI-defined gross disease) and both were expanded by 5mm (3mm posterior). The prostate PTV received 36.25 Gy in 5 fractions and the SIB PTV received 40 Gy. After a median >50 months median follow up, there were no biochemical or clinical recurrences. Median post-treatment PSA was 0.23. There were also no grade 3 toxicity events. The rate of late CTCAE grade 2 GU toxicity was 38.5%, and the rate of late grade 2 GI toxicity was 11.5%.
TBL: This small trial demonstrated excellent long-term disease control when treating the entire prostate to 36.25 Gy in 5 fractions with a 40 Gy SIB to MRI-defined disease. | Maas, Pract Radiat Oncol 2023