Background
The adoption of Stereotactic Body Radiation Therapy (SBRT) for prostate cancer has allowed treatment to be completed in less than 2 weeks, but has predominantly been given to the prostate only. Currently, very few prospective studies have compared delivery of SBRT versus hypofractionated radiotherapy (HFX) when giving concurrent pelvic radiation. The aim of the study is to evaluate the tolerance and efficacy of pelvic node radiotherapy and SIB to the prostate in prostate patients requiring nodal irradiation.
Methods
A total of 58 patients were irradiated with SBRT and initiated ADT therapy between 2014 and 2023. 57 patients were treated with 7.5 Gy to the prostate and 1 to 7.25 Gy. All patients were treated with 5 Gy x 5 fraction to the pelvis. This group was compared to a preselected historical cohort of 65 HFX patients with 57 of these patients treated with 67.5/50 Gy in 25 fractions, 1 with patient 67.5/45 Gy in 25 fractions, and 6 patients with 60/44-46 Gy in 20 fractions. Patients were evaluated for GU and GI toxicities according to Radiation Therapy Oncology Group Toxicity criteria at one year post radiation therapy.
Results
There were 31 grade 0 (53.4%), 1 grade 1 (1.7%), 25 grade 2 (43.1%), 1 grade 3 (1.7%) events in the SBRT group and 29 GU grade 0 (44.6%), 3 grade 1 (4.6%), and 33 grade 2 (50.8%) GU toxicities in the HFX group with no significant difference between the groups (p=0.464). There were 55 grade 0 (94.8%), 1 grade 1 (1.7%), and 2 grade 2 (3.4%) GI toxicities in the SBRT group and 59 grade 0 (90.8%), 1 grade 1 (1.5%), and 5 grade 2 (7.7%) events in the HFX group with no significant difference between the groups (p=0.381).
Conclusions
This prospective study provides data to support the use of concurrent pelvic radiation with SBRT to the prostate. Our findings suggest there is no difference in toxicity between HFX and 25 Gy pelvic radiation (5 Gy/5 fractions) concurrent with SBRT to the prostate, therefore it appears to be a safe and convenient option for veterans with prostate cancer.
