In this prospective phase II trial, we investigated the toxicity and patient reported quality of life outcomes in patients treated with SBRT to the prostate gland and a simultaneous focal boost to MRI identified intraprostatic lesions while also de-escalating dose to the adjacent organs at risk.
Eligible patients included low- or intermediate- risk prostate cancer (Gleason score ≤ 7, PSA ≤20, T stage ≤2b). SBRT was prescribed to 40 Gy in 5 fractions delivered every other day to the prostate, with any areas of high disease burden (MRI-identified PI-RADS 4 or 5 lesions) simultaneously escalated to 42.5-45 Gy and areas overlapping organs at risk (within 2 mm of urethra, rectum, and bladder) constrained to 36.25 Gy (n=100). Patients without a pre-treatment MRI or without MRI-identified lesions were treated to dose of 37.5 Gy with no focal boost (n=14).
From 2015 to 2022, a total of 114 patients were enrolled with a median follow-up of 42 months. No acute or late grade 3+ GI toxicity was observed. One patient developed late grade 3 GU toxicity at 16 months. In patients treated with focal boost (n=100), acute grade 2 GU and GI toxicity was seen in 38% and 4% of patients, respectively. Cumulative late grade 2+ GU and GI toxicities at 24 months were 13% and 5% respectively. Patient reported outcomes showed no significant long-term change from baseline in urinary, bowel, hormonal, or sexual quality of life scores following treatment.
SBRT to a dose of 40 Gy to the prostate gland with a simultaneous focal boost up to 45 Gy is well tolerated with similar rates of acute and late grade 2+ GI and GU toxicity as seen in other SBRT regimens without intraprostatic boost. Moreover, no significant long-term changes were seen in patient reported urinary, bowel, or sexual outcomes from pre-treatment baseline.
International journal of radiation oncology, biology, physics. 2023 May 11 [Epub ahead of print]
B A Morris, E E Holmes, N J Anger, G Cooley, J M Schuster, N Hurst, A M Baschnagel, M F Bassetti, G C Blitzer, R J Chappell, R A Bayliss, Z S Morris, M A Ritter, J M Floberg
University of Wisconsin School of Medicine and Public Health, Department of Human Oncology, Madison, WI. Electronic address: ., University of Wisconsin School of Medicine and Public Health, Department of Biostatistics & Medical Informatics, Madison, WI. Electronic address: ., University of Wisconsin School of Medicine and Public Health, Department of Human Oncology, Madison, WI., University of Wisconsin School of Medicine and Public Health, Department of Biostatistics & Medical Informatics, Madison, WI. Electronic address: .