Contraindications for External Beam Radiation Therapy (EBRT)
EBRT is absolutely contraindicated in patients with prior pelvic irradiation, active inflammatory disease of the rectum, or a permanent indwelling Foley catheter. 1, 2
Absolute Contraindications
Prior pelvic irradiation is an absolute contraindication due to the risk of cumulative radiation toxicity and severe tissue damage from overlapping radiation fields 1, 2
Active inflammatory disease of the rectum (such as active proctitis) is an absolute contraindication because it significantly increases the risk of severe radiation-induced complications including fistula formation and soft tissue necrosis 1, 2
Permanent indwelling Foley catheter is an absolute contraindication as the presence of a permanent catheter is incompatible with the precise targeting required for EBRT and increases infection risk 1, 2
Prior endobronchial radiation in the same area within 6 months is an absolute contraindication for thoracic EBRT 1
Relative Contraindications
Very low bladder capacity may lead to increased urinary toxicity and reduced quality of life post-treatment, making EBRT delivery challenging 1, 2
Chronic moderate or severe diarrhea is a relative contraindication as pre-existing bowel dysfunction may be significantly exacerbated by radiation effects 1, 2
Bladder outlet obstruction requiring a suprapubic catheter may complicate treatment delivery and increase the risk of urinary complications 1, 2
Inactive ulcerative colitis carries an increased risk of disease flare-up following radiation exposure, though recent evidence suggests this may be less prohibitive than historically believed 1, 2, 3
Advanced age, psychiatric problems, and prior laparotomy are relative contraindications for rectal cancer radiotherapy 1
Special Considerations for Connective Tissue and Inflammatory Diseases
Genetic conditions predisposing to skin cancer (basal cell nevus syndrome, xeroderma pigmentosum) are absolute contraindications for skin cancer radiotherapy due to impaired DNA repair mechanisms 1
Connective tissue diseases (lupus, scleroderma) have traditionally been considered contraindications, though recent systematic reviews show that collagen vascular disease patients have only 11.7% risk of grade ≥3 acute toxicity and 6.1% risk of late toxicity 1, 4
Inflammatory bowel disease (IBD) should be approached with caution: brachytherapy shows similar toxicity rates to non-IBD patients (7% acute grade ≥3 toxicity), while EBRT shows moderately increased toxicity (20% acute grade ≥3 toxicity) 3, 4, 5
Important Clinical Caveats
Verrucous carcinoma is contraindicated for radiotherapy due to documented increased metastatic risk after radiation treatment 1
For patients with IBD requiring pelvic radiation, brachytherapy should be strongly preferred over EBRT when technically feasible, as it demonstrates significantly lower toxicity rates (5% vs 15% late grade ≥3 toxicity) 3
The risk of grade 4 toxicity in patients with historically accepted contraindications (collagen vascular disease, IBD) is less than 5%, and grade 5 toxicity is negligible (<1%), suggesting these conditions are not absolute contraindications when radiation is clinically necessary 4
EBRT should only be performed at facilities with appropriate technology, physics expertise, and clinical experience, particularly for advanced techniques like IMRT and SBRT 2