Jones RT, et al. – Researchers undertook this study to compare the rectal–sparing capabilities of rectal balloons vs absorbable injectable spacer gel in stereotactic body radiation therapy (SBRT) for prostate cancer. The injectable spacer gel outperformed the rectal balloon in the majority of the examined and relevant dosimetric rectal–sparing parameters, in this analysis of patients enrolled on 2 consecutive multi–institutional prospective trials of SBRT for prostate cancer. The data showed that rectal balloon did not outperform the injectable spacer gel in any measured rectal dose parameter.