Section: Colorectal Sub-section: Colitis Curriculum: Curriculum, page 23
Definition
Radiation proctitis is inflammation of the rectum that occurs as a result of acute damage to the rectum sustained from pelvic radiation
Acute: Acute radiation proctitis occurs during or within six weeks of radiation therapy.
- Acute radiation proctitis is caused by direct mucosal damage from radiation exposure
Chronic: Chronic radiation injury may occur as a continuation of acute radiation proctitis or have a delayed onset
- Chronic radiation proctitis results from progressive epithelial atrophy and fibrosis associated with obliterative endarteritis and chronic mucosal ischemia. Risk:
- Dose
- Method of delivery
- Genetic
- IBD
Epidemiology
Pathophysiology
Summary
Acute radiation рrоϲtitiѕ is caused by direct mucosal damage from radiation exposure. Chronic radiation рrоctitiѕ results from progressive epithelial atrophy and fibrosis associated with obliterative endarteritis and chronic mucosal ischemia.
Detailed
- Acute (within 3 months)
- Crypt epithelium is rapidly proliferating
- Radiation causes cells death
- Initial damage occurs within hours
- Crypt cell death - insufficient replacement of villous epithelium, mucosal barrier breakdown and mucosal inflammation
- Leukocyte infiltration, crypt abscesses, ulceration
- Chronic (after 3 months)
- ⇒ Mucosal atrophy, vascular sclerosis, progressive gut wall fibrosis
- Mucosal atrophy
- Intestinal wall fibrosis - submucosal, as ulcers heal
- Microvascular sclerosis - endarteritis obliterans
- Accelerated atherosclerosis
Clinical presentation
Acute
- Abdominal or pelvic pain, diarrhea, mucus discharge, urgency, and tenesmus. Rectal bleeding is rare.
Chronic
- The most common manifestation is rectal bleeding and iron deficiency anemia due to bleeding secondary to Radiation associated vascular ectasia (RAVE).
- Urgency, change in stool caliber and consistency, constipation resulting from underlying fibrosis, and, rarely, fecal incontinence due to overflow diarrhea and increased mucus.
Diagnosis
Endoscopy
- Nonspecific
- edematous, erythematous mucosa that may have ulceration or sloughing.
- hallmark feature includes the presence of vascular ectasias
- Mucosal features consistent with chronic radiation injury include pallor with friability and telangiectasias
- Histology
- fibrosis of the lamina propria and a variable degree of epithelial injury, crypt distortion, and Paneth cell metaplasia
- Important distinguishing characteristics include a lack of inflammatory cell infiltrates and ulcerations
Management
Acute
- short interruptions in their treatment to improve symptoms
Chronic
- Chronic symptoms can be treated with enemas and stool softners
- Bleeding treated with Argon plasma coagulation (APC), Bipolar electrocoagulation (BiCap) and heater probe and Radiofrequency ablation (RFA)
- Surgery reserved for intractable symptoms
- Hyperbaric oxygen (HBO) has been shown to improve outcomes