Radiation proctitis is a condition characterized by inflammation and damage to the rectum that occurs following radiation therapy to the pelvic area. This side effect develops because the rectum sits close to target organs, such as the prostate, cervix, or bladder, which are often treated for cancer using high-energy radiation. The exposure to this energy, while intended to eliminate cancer cells, can also injure the healthy tissues of the rectal lining. Because many cancers require pelvic radiation, this condition is a relatively common complication for survivors.
How Radiation Therapy Leads to Rectal Damage
High-energy radiation is designed to destroy rapidly dividing cancer cells, but it also affects the healthy, fast-growing cells that line the rectum. The initial damage is caused by the direct effects of the radiation, which generate free radicals that disrupt cellular DNA and cause immediate tissue injury. This process leads to two distinct phases of injury: acute proctitis and chronic proctopathy.
Acute radiation proctitis develops during treatment or within the first six months after completion. This phase results from direct mucosal injury, causing inflammation, swelling, and superficial ulceration of the rectal lining. Most patients experience some degree of this acute injury, but it is often self-limiting and resolves within a few weeks or months after treatments end.
Chronic, or late, radiation proctopathy can manifest months or even years after radiation has stopped, sometimes up to a decade later. This long-term damage involves the underlying tissues and small blood vessels, leading to obliterative endarteritis. This process causes tiny blood vessels to become narrowed and blocked, significantly reducing blood flow to the rectal tissue and resulting in persistent tissue ischemia.
Reduced blood supply causes the body to create new, fragile blood vessels called telangiectasias, which are prone to bleeding. Chronic inflammation also triggers the build-up of scar-like tissue, known as fibrosis, in the rectal wall. Fibrosis can cause the rectum to lose its natural elasticity and flexibility, sometimes leading to strictures or narrowing of the passage.
Common Indicators of Radiation Proctitis
Symptoms vary widely depending on whether the injury is acute or chronic and the extent of tissue damage. In the acute phase, characterized by mucosal inflammation, patients commonly report frequent bowel movements and diarrhea. They may also experience tenesmus, a persistent, painful sensation of needing to pass stool even when the bowel is empty.
Rectal urgency is a frequent complaint in the acute phase, where the need to defecate is sudden and difficult to control. Mucus discharge is also common as the inflamed lining sheds cells and produces excessive fluid. While acute proctitis can cause mild rectal bleeding, significant blood loss is uncommon during this initial period.
Chronic radiation proctopathy symptoms tend to be more persistent and often focus on rectal bleeding, known as hematochezia. This bleeding results from fragile, newly formed telangiectasias on the rectal surface, which can easily rupture and lead to chronic blood loss. Persistent bleeding can sometimes be severe enough to cause anemia, requiring medical intervention.
Long-term changes from fibrosis and loss of rectal elasticity also contribute to chronic symptoms. Patients may continue to experience tenesmus and urgency, and can develop fecal incontinence if sphincter muscles were affected by radiation. In severe cases where fibrosis has caused a stricture, they may experience difficulty passing stool or a change in the caliber of feces. Rectal pain or discomfort is also an indicator of chronic tissue injury.
Strategies for Managing and Treating Proctitis
Management begins with conservative measures, particularly for patients experiencing acute symptoms like diarrhea and urgency. Dietary adjustments are recommended, such as adopting a low-fat, low-fiber diet and avoiding irritants like caffeine, alcohol, and spicy foods. Maintaining adequate hydration is also important, especially when dealing with diarrhea and frequent bowel movements.
Medical therapies reduce inflammation and protect the damaged rectal lining. Topical treatments, such as sucralfate enemas, coat the mucosa to create a protective barrier that promotes healing. Corticosteroid enemas or suppositories are employed for their anti-inflammatory properties to soothe the irritated tissue.
Oral medications may also be prescribed to manage specific symptoms, including anti-diarrheal agents to slow down bowel motility and reduce urgency. In some cases, oral 5-aminosalicylates, such as mesalazine, are used for their anti-inflammatory effects within the bowel. These approaches aim to alleviate discomfort and support the body’s natural healing processes.
For chronic cases involving significant and persistent rectal bleeding, procedural interventions are necessary. Argon Plasma Coagulation (APC) is a common endoscopic technique that uses a jet of argon gas ionized by an electrical current to cauterize and seal the fragile, bleeding telangiectasias. Although multiple sessions may be required, APC is highly effective at controlling chronic hemorrhagic proctitis. Hyperbaric Oxygen Therapy (HBOT) involves breathing pure oxygen in a pressurized chamber, which increases oxygen delivery to the ischemic tissues and stimulates the growth of new, healthier blood vessels.