Stereotactic Body Radiotherapy for Prostate Cancer

Evidence for SBRT Regimens

The European Association of Urology recommends the 36 Gy in 6 fractions SBRT regimen for salvage treatment of intraprostatic recurrence after prior radiotherapy, based on evidence from the prospective phase 2 GETUG-AFU 31 study 1, 2
The National Comprehensive Cancer Network recommends SBRT regimens of 36.25 Gy in 5 fractions or 42.7 Gy in 7 fractions for definitive treatment of newly diagnosed prostate cancer, with 5-year biochemical relapse-free survival rates of 95% for low-risk, 84% for intermediate-risk, and 81% for high-risk patients 3, 4

The American Society for Radiation Oncology recommends that SBRT should only be performed at centers with appropriate technology, physics expertise, and clinical experience with image-guided delivery systems 5, 4
The European Society for Radiotherapy and Oncology recommends strict quality assurance standards and precise targeting capabilities for SBRT, with rectal wall, bladder wall, and urethral sparing constraints strictly respected 5

The National Comprehensive Cancer Network recommends SBRT monotherapy to prostate only using validated regimens (36.25 Gy/5fx or 42.7 Gy/7fx) for low-risk disease, with no nodal irradiation indicated 4
The European Association of Urology recommends combining SBRT with 6 months of androgen deprivation therapy (ADT) for unfavorable intermediate-risk disease, and using conventional IMRT to pelvis (45 Gy) with prostate boost rather than SBRT to nodes if nodal coverage is needed 4, 3
The American Society of Clinical Oncology recommends SBRT combined with at least 24 months ADT for high-risk disease, with Level I evidence demonstrating improved overall survival compared to RT alone 4

The NCCN defines unfavorable intermediate‑risk prostate cancer as the presence of any one of the following: primary Gleason pattern 4 (Gleason 4+3), ≥ 50 % positive biopsy cores, or > one NCCN intermediate‑risk factor (clinical stage T2b‑c, PSA 10‑20 ng/mL, Gleason 7)【6】【7】.
Patients classified as unfavorable intermediate‑risk have significantly higher rates of distant metastasis and prostate‑cancer‑specific mortality compared with favorable intermediate‑risk patients, indicating a greater need for combined‑modality therapy【6】【7】.

For unfavorable intermediate‑risk disease, SBRT must be combined with six months of androgen‑deprivation therapy; this recommendation is based on strong evidence from conventional‑fractionation studies showing outcome benefit with short‑term ADT【8】【9】.

Conventional external‑beam radiotherapy (74–78 Gy) plus 4–6 months of ADT provides Level I evidence of improved 10‑year overall survival (increase from 54 % to 61 %; p = 0.03)【9】.
Radical prostatectomy with pelvic lymph‑node dissection is an evidence‑based alternative for unfavorable intermediate‑risk patients【9】.

Although the NCCN lists SBRT as a guideline option, the supporting evidence for SBRT in unfavorable intermediate‑risk prostate cancer is less robust than that for conventional fractionation with ADT【9】.

Before SBRT, cross‑sectional imaging (CT or MRI) and bone scintigraphy should be performed in unfavorable intermediate‑risk patients to exclude occult metastatic disease【9】.