Pelvic radiation therapy is used to destroy cancer cells in malignancies of the prostate, gynecological organs, and rectum. While radiation successfully targets tumors, it can damage surrounding healthy tissues, leading to chronic, delayed side effects known as Radiation-Induced Injury (RII). This damage involves inflammation, reduced blood vessel density (vascular changes), and the buildup of scar tissue (fibrosis). These structural changes can manifest months or even years after treatment, presenting challenges to quality of life. Addressing these late effects requires a multi-faceted approach that manages symptoms and attempts to reverse the underlying tissue damage.
Managing Gastrointestinal and Rectal Symptoms
Chronic radiation proctitis, an inflammation of the rectal lining, is a common side effect causing symptoms like rectal bleeding, urgency, and chronic diarrhea. Initial management focuses on dietary adjustments to ease the burden on the bowel. Patients are advised to follow a low-residue diet temporarily to reduce stool volume and to manage carbohydrate intake, as radiation can cause transient lactose intolerance that exacerbates diarrhea.
Pharmacological interventions target specific symptoms to stabilize bowel function. Chronic diarrhea, particularly if persistent, may be due to bile acid malabsorption, which occurs when radiation damages the lower small intestine’s ability to reabsorb bile acids. A bile acid binder such as Cholestyramine sequesters excess bile acids in the gut, preventing irritation of the colon. For localized rectal inflammation and pain, topical treatments like sucralfate enemas are used, as sucralfate forms a protective barrier over the damaged mucosal tissue to promote healing.
Bleeding from the rectum is a frequent presentation of radiation proctitis, typically caused by fragile, dilated blood vessels called telangiectasias that form on the irradiated surface. Endoscopic treatments provide a direct method for sealing these bleeding vessels. Argon Plasma Coagulation (APC) is a technique where a jet of ionized argon gas is applied through an endoscope to coagulate the abnormal vessels, stopping the chronic blood loss.
Endoscopic thermal treatments like APC control bleeding and reduce the need for blood transfusions. For refractory cases of bleeding, or when APC is unavailable, other thermal methods like bipolar electrocoagulation or radiofrequency ablation (RFA) can be considered. These targeted procedures minimize damage to the underlying tissue while addressing the source of the hemorrhage.
Addressing Urinary and Bladder Dysfunction
Radiation-induced damage to the bladder, known as chronic radiation cystitis, can lead to urinary symptoms including increased frequency, urgency, and pain. Behavioral strategies are the first line of defense, involving fluid management to avoid bladder irritants like caffeine and acidic beverages, alongside timed voiding to gradually increase the interval between urination. These practices help retrain the bladder muscle to hold greater volumes.
When behavioral changes are not sufficient, oral medications manage overactive bladder symptoms. Anticholinergic drugs block nerve signals that cause the bladder muscle to contract, reducing urgency and frequency. Beta-3 adrenergic agonists, such as Mirabegron or Vibegron, work by relaxing the bladder muscle during the filling phase, which increases the bladder’s storage capacity.
Treatment focuses on repairing the bladder’s inner lining, which radiation can compromise. The urothelium is normally protected by a layer of glycosaminoglycans (GAGs), a matrix damaged by radiation. Intravesical treatments, delivered directly into the bladder via a catheter, aim to replenish this protective lining. Instillations of substances like hyaluronic acid and chondroitin sulfate help restore the GAG layer, shielding the bladder wall from irritating urine components and reducing inflammation.
Severe radiation cystitis can present with persistent blood loss in the urine (hematuria). Management of this bleeding often escalates from cystoscopy with direct thermal coagulation of the vessel to intravesical washes using agents like alum or formalin, which chemically cauterize the bleeding surface. In challenging scenarios, where bleeding is uncontrollable by conservative means, selective embolization of the internal iliac arteries may be performed to reduce blood flow to the bladder.
Restoring Sexual and Reproductive Function
Pelvic radiation can negatively impact sexual health in both men and women due to damage to nerves, blood vessels, and tissue. For men, the most common consequence is erectile dysfunction (ED), resulting from vascular and nerve injury. Treatment often begins with oral phosphodiesterase type 5 (PDE5) inhibitors, such as Sildenafil, which increase blood flow to the penis to facilitate an erection.
If oral medications are ineffective, mechanical aids and localized therapies are considered. Vacuum erection devices (VEDs) create negative pressure around the penis to draw blood into the erectile tissues, using a constriction ring placed at the base to maintain the erection. A penile rehabilitation program is often initiated early, sometimes involving a daily low dose of a PDE5 inhibitor, to maintain tissue oxygenation and reduce the progression of fibrosis.
In women, radiation can cause vaginal dryness, pain during intercourse (dyspareunia), and a shortening and narrowing of the vaginal canal, known as vaginal stenosis, due to tissue scarring. To prevent stenosis, regular vaginal dilator therapy is recommended to maintain the length and flexibility of the vagina. This mechanical stretching is started while the tissue is still healing.
To address dryness and atrophy, local hormonal therapies and specialized lubricants are utilized. Localized estrogen creams or rings restore the health and elasticity of the vaginal tissues without the systemic effects of oral hormone replacement. Pelvic floor physical therapy can be beneficial for women experiencing chronic pelvic pain or muscle tension related to the radiation injury.
Systemic and Advanced Tissue Repair Strategies
Therapies that address the underlying tissue damage caused by radiation, rather than just managing symptoms, represent an advanced approach. Radiation injury causes a lack of oxygen (hypoxia) and poor blood supply in the affected tissues, limiting the body’s ability to heal. Targeting this poor blood flow is central to tissue repair.
Hyperbaric Oxygen Therapy (HBOT) directly addresses tissue hypoxia. Patients breathe 100% oxygen in a pressurized chamber, which increases the amount of oxygen dissolved in the blood plasma. This oxygenated blood is delivered to the damaged pelvic tissues, promoting the growth of new blood vessels (neovascularization) and encouraging fibroblast activity for tissue repair. HBOT is used to treat refractory radiation proctitis, chronic radiation cystitis, and osteonecrosis.
HBOT typically involves a protocol of 30 to 60 sessions, each lasting 90 to 120 minutes, with the goal of improving the tissue environment. The increased oxygen tension mobilizes stem cells from the bone marrow, which migrate to the injured sites to assist in tissue regeneration and wound healing. This systemic therapy offers a non-surgical pathway to restore the compromised blood supply and reverse radiation-induced scarring.
Surgical intervention is reserved as a last resort for severe structural complications that are refractory to all other therapies. These complications include complete bowel or urethral strictures, non-healing ulcers, or the formation of abnormal connections between organs, known as fistulas. Due to the compromised blood supply and dense scar tissue in the irradiated field, these surgeries carry a higher risk of complications, such as poor wound healing and anastomotic breakdown. Procedures range from endoscopic balloon dilation for strictures to complex resections and urinary diversion, requiring specialized surgical expertise to navigate the challenging, fibrotic tissue.