Radiation therapy uses high-energy rays to damage the DNA of rapidly dividing cancer cells. Yes, radiation therapy can cause bleeding; this is a recognized side effect that varies depending on the treatment location. Bleeding occurs because the radiation beam must pass through normal, healthy tissue to reach the tumor, causing unintended damage. Understanding the biological mechanisms, timing, and location-specific symptoms is important for patients undergoing or having completed treatment.
How Radiation Affects Blood Vessels
The cause of radiation-induced bleeding lies in damage to the microvasculature, specifically the endothelial cells lining the blood vessels. Ionizing radiation generates free radicals that damage the cell membranes and DNA of these cells. This initial cellular injury triggers a localized inflammatory response within the irradiated tissue.
This damage compromises the structural integrity of the vessel walls, leading to increased vascular permeability and fragility. Over time, the body responds by forming scar-like fibrous tissue, known as fibrosis, which causes the vessel walls to thicken and stiffen.
The combination of endothelial damage and fibrosis leads to the narrowing and eventual blockage of small arteries, a process called obliterative endarteritis. This restricts blood flow, causing chronic tissue oxygen deprivation, or ischemia. The resulting fragile, poorly oxygenated tissue is highly prone to rupture and bleeding, sometimes spontaneously or with minimal trauma.
The Timeline of Bleeding: Acute vs. Chronic Effects
Radiation-induced bleeding is categorized into acute and chronic timelines. Acute bleeding typically occurs during treatment or within the first three months after completion. This early phase results primarily from immediate tissue inflammation and the rapid loss of epithelial cells lining mucosal surfaces.
This cellular destruction causes inflammation, such as mucositis or acute proctitis in the rectum, leading to superficial erosions and ulcerations. Bleeding in this phase is usually mild, often presenting as streaks of blood, and is generally self-limiting. Symptoms tend to resolve gradually once treatment finishes and surviving stem cells regenerate the damaged lining.
Chronic bleeding develops much later, often six months to many years after treatment. This late-onset bleeding is caused by long-term tissue remodeling, including severe fibrosis and the formation of abnormal, dilated capillaries called telangiectasias. These fragile vessels have thin walls, making them susceptible to rupture from minor mechanical stress, such as passing a firm stool. Chronic bleeding is often persistent and may require medical intervention due to significant blood loss.
Location-Specific Bleeding and Symptoms
The presentation of radiation-induced bleeding depends on the irradiated area. One common site is the gastrointestinal (GI) tract following pelvic radiation for prostate, bladder, or gynecological cancers. Rectal bleeding is known as radiation proctitis, presenting as hematochezia (bright red blood passed with or without stool). In the chronic phase, this bleeding may be mild and intermittent, often originating from telangiectasias on the rectal wall.
Radiation targeting the genitourinary (GU) system, such as the bladder, can cause radiation cystitis, characterized by hematuria (blood in the urine). Acute symptoms include painful and frequent urination. The chronic form can involve severe, recurrent bleeding known as hemorrhagic cystitis. This condition results from long-term changes in the bladder’s small blood vessels, potentially leading to significant blood loss and clots that obstruct urine flow.
In the head and neck region, radiation can cause severe oral mucositis, where the lining of the mouth and throat becomes inflamed and ulcerated. Bleeding here can be exacerbated by brushing or eating. Less commonly, radiation to the chest or lungs can lead to hemoptysis (coughing up blood), usually associated with extensive tissue damage or secondary infections.
Treatment Strategies and Medical Intervention
Management of radiation-induced bleeding begins with conservative measures for mild or acute cases. Supportive care includes dietary modifications, stool softeners, and increased hydration to prevent mechanical irritation of mucosal surfaces. For chronic GI bleeding, iron supplementation may be necessary to treat resulting anemia.
Topical medications are frequently used to treat localized inflammation and bleeding. For radiation proctitis, this may involve sucralfate enemas, which create a protective coating over the damaged rectal lining to promote healing. Steroid or anti-inflammatory enemas may also be employed to reduce the inflammatory response.
When bleeding is severe, recurrent, or unresponsive to conservative therapy, interventional treatments are necessary.
Endoscopic Procedures
Endoscopic procedures are the standard approach, most often utilizing Argon Plasma Coagulation (APC) to stop chronic bleeding from telangiectasias. APC applies argon gas and electrical energy to thermally coagulate and seal the fragile blood vessels on the mucosal surface.
Hyperbaric Oxygen Therapy (HBOT)
A non-invasive option is Hyperbaric Oxygen Therapy (HBOT), which involves breathing 100% oxygen in a pressurized chamber. HBOT increases oxygen concentration in the damaged tissue, stimulating the growth of new, healthy blood vessels and promoting long-term tissue repair. While APC treats the bleeding source directly, HBOT addresses the underlying tissue damage caused by radiation.