Safe bet.

Since extreme hypofractionation for prostate cancer has become kosher in general practice, the next big thing is to deliver even higher doses of radiation to the dominant nodule. This obviously requires MRI, and generally involves a simultaneous integrated boost (SIB). While it sounds intuitive enough, 1) you may not be sure the targeted nodule is the driver of disease while 2) there are usually some very sensitive adjacent critical structures. Enter this phase 1 Swedish trial looking at an SIB to 50 Gy during standard radiation of 36.25 Gy to the entire prostate all in 5 fractions for intermediate or high-risk disease. An important exclusion was tumor within 3 mm of the urethra, and all patients had a rectal spacer placed prior to treatment. While 70% had G1-2 urinary toxicity, no toxicity was recorded as grade 3. TBD if a rectal spacer itself should count as grade 3 toxicity. TBL: Here is more early phase data that taking prostate nodules to lung SBRT doses is at least safe. | Herrera, Int J Radiat Oncol Biol Phys 2018