Contraindications for Stereotactic Body Radiation Therapy (SBRT) in Prostate Cancer

Absolute Contraindications

The National Comprehensive Cancer Network recommends that prior pelvic irradiation is an absolute contraindication for SBRT in prostate cancer due to increased risk of cumulative radiation toxicity 1, 2, 3
Active inflammatory disease of the rectum is an absolute contraindication for SBRT in prostate cancer, as conditions such as active proctitis significantly increase the risk of severe radiation-induced complications 1, 2
A permanent indwelling Foley catheter is an absolute contraindication for SBRT in prostate cancer, as the presence of a permanent catheter is incompatible with the precise targeting required for SBRT 1, 4

The National Comprehensive Cancer Network suggests that very low bladder capacity may lead to increased urinary toxicity and reduced quality of life post-treatment, and should be considered a relative contraindication for SBRT in prostate cancer 1, 3
Chronic moderate or severe diarrhea is a relative contraindication for SBRT in prostate cancer, as pre-existing bowel dysfunction may be exacerbated by radiation effects 1, 2
Bladder outlet obstruction requiring a suprapubic catheter may complicate treatment delivery and increase risk of urinary complications, and should be considered a relative contraindication for SBRT in prostate cancer 1, 4
Inactive ulcerative colitis is a relative contraindication for SBRT in prostate cancer, as there is an increased risk of flare-up following radiation exposure 1, 2

SBRT differs from conventional radiation therapy in that it delivers highly conformal, high-dose radiation in 5 or fewer treatment fractions, and requires precise image-guided delivery systems 1, 4
The National Comprehensive Cancer Network recommends that SBRT should only be performed at facilities with appropriate technology, physics, and clinical expertise 1
Careful patient selection is necessary to minimize toxicity risk with SBRT in prostate cancer 1

Urinary toxicity is a potential side effect of SBRT in prostate cancer, with temporary bladder symptoms affecting up to 50% of patients, and a risk of late urinary toxicity 1
Rectal toxicity is a potential side effect of SBRT in prostate cancer, with a low but definite risk of protracted rectal symptoms from radiation proctitis 1
Sexual dysfunction is a potential side effect of SBRT in prostate cancer, with risk increasing over time following treatment 1

The European Association of Urology recommends two specific ultrahypofractionated SBRT schedules for prostate cancer: 36.25 Gy in 5 fractions and 42.7 Gy in 7 fractions, delivered on alternate days, for patients with prostate cancer 5, 6
The European Society for Radiotherapy and Oncology suggests that these regimens should only be offered at facilities with appropriate technology, physics, and clinical expertise, although the specific details of this requirement are not provided in the cited references 5, 6

The European Association of Urology guidelines emphasize the importance of respecting organ at risk constraints, including rectal wall, bladder wall, and urethral sparing, when delivering ultrahypofractionated regimens of 36.25 Gy in 5 fractions or 42.7 Gy in 7 fractions, for patients with prostate cancer 5, 6
The American Society for Radiation Oncology recommends that the urethral planning risk volume (PRV) should be defined as a 2 mm expansion of the urethra, and that the urethral PRV should be limited to 5 × 7.25 Gy (36.25 Gy total) when dose-escalating to 5 × 9 Gy to the prostate, for patients with prostate cancer 5, 6

The European Society for Radiotherapy and Oncology suggests that a standardized stepwise optimization approach can significantly improve OAR sparing without compromising target coverage, for patients with prostate cancer 5, 6
The American Association of Physicists in Medicine recommends that the initial optimization should achieve PTV coverage (D98% ≥ 36.2 Gy, D2% ≤ 46.9 Gy for 5 × 7.25 Gy regimen), and that the urethral constraint application should limit urethral PRV dose while maintaining PTV-PRV coverage (D95% ≥ 40.6 Gy), for patients with prostate cancer 5, 6

The European Association of Urology guidelines warn against proceeding with SBRT if OAR constraints cannot be met without compromising target coverage, and recommend considering conventional fractionation or alternative modalities, for patients with prostate cancer 5, 6