Radiation therapy (RT) is a common and effective method used to treat prostate cancer, utilizing high-energy beams to destroy cancerous cells. The treatment is highly successful, but because the prostate sits near other organs, healthy tissues may receive some radiation dose. Long-term side effects are those complications that persist or first appear six months or more after treatment, sometimes even years later. Understanding these potential effects is important for men making treatment decisions and setting realistic expectations about their quality of life.
Long-Term Effects on Urinary Function
Radiation exposure to the bladder and urethra can lead to chronic changes in urinary function due to inflammation and scarring of the tissue. This long-term irritation, often called chronic radiation cystitis, can manifest as a persistent need to urinate frequently or with great urgency. Symptoms like a burning sensation during urination or blood in the urine (hematuria) can also occur months or years after treatment.
Damage to the bladder lining and muscle can reduce the organ’s capacity and elasticity, contributing to these issues of urgency and frequency. Furthermore, the development of scar tissue can cause a narrowing of the urethra, known as a urethral stricture. This narrowing can make it progressively harder to pass urine and may require a surgical procedure to widen the passage.
Chronic urinary incontinence, while a less frequent long-term side effect of radiation alone compared to surgery, can still occur. For most men who experience it, this involves occasional dribbling or minor leakage, often associated with coughing, laughing, or strenuous activity (stress incontinence). This incontinence is generally due to damage to the bladder neck and surrounding structures, which compromises the ability to fully control the flow of urine.
Chronic Gastrointestinal and Bowel Changes
Because the rectum lies immediately next to the prostate gland, it is often exposed to a portion of the radiation dose, leading to chronic gastrointestinal issues. The long-term inflammation of the rectal lining is known as chronic radiation proctitis. This condition can develop months or years after treatment and is caused by damage to the small blood vessels and tissue in the rectum.
Symptoms of chronic proctitis include rectal bleeding (hematochezia), which results from fragile, damaged blood vessels prone to rupture. Other common long-term effects include chronic diarrhea, fecal urgency, and the passage of mucus. Studies indicate that the risk of grade 2 or higher long-term gastrointestinal issues can range from 2% to 26%, depending on the specific radiation technique used.
Damage to the rectal muscles and nerves can lead to minor fecal incontinence, or difficulty controlling bowel movements. Chronic bowel dysfunction may not improve over time and can sometimes worsen as the effects of radiation accumulate. Treatments often focus on managing symptoms with diet modifications, fiber supplements, and anti-diarrheal agents, though laser therapy is sometimes used to seal off bleeding vessels.
Sustained Impact on Sexual Health
Erectile dysfunction (ED) is one of the most common and significant long-term effects of prostate radiation therapy, and it often differs from the ED caused by surgery. The onset of erectile issues after radiation is typically gradual and progressive, often developing over one to three years following treatment. This delay occurs because the radiation slowly damages the small blood vessels and nerves necessary for achieving and maintaining an erection.
Vascular damage is the primary mechanism, where the radiation causes fibrosis and scarring of the penile tissues and blood vessels, which reduces blood flow into the penis. Damage to the cavernous nerves, which transmit signals for erection, also contributes to the dysfunction. Research suggests that approximately 50% of men who had normal erectile function before treatment may experience a decline within five to six years.
Men may also experience changes in ejaculation, which is distinct from erectile function. Radiation can cause the prostate and seminal vesicles to scar and produce less fluid, resulting in dry ejaculation or a significantly reduced volume of semen. Libido is generally not directly affected by the radiation itself, but it can be impacted by associated hormonal therapies or psychological distress related to changes in sexual function.
Systemic and Statistically Rare Risks
A concern for many patients is the long-term risk of developing a second cancer in the field that received radiation. Although radiation is a known carcinogen, the risk of developing a secondary malignancy, such as bladder or rectal cancer, remains very low. One large study found only a minimal increase in the rate of developing a second cancer, specifically a 0.5% higher risk compared to men with prostate cancer who did not receive radiation.
Persistent fatigue is another long-term systemic effect for some patients that lasts well beyond the treatment period. While acute fatigue is common during treatment, a milder, chronic form can continue for months or even years. This ongoing exhaustion can affect a person’s energy levels and general quality of life.
Statistically rare, but serious, localized complications include severe chronic pain syndromes or bone damage. The radiation can, in infrequent cases, damage the bone cells and blood supply in the pelvic area, leading to a condition like avascular necrosis or an increased risk of bone fractures. Severe nerve damage (neuropathy) that causes persistent pain or weakness in the legs is also an extremely rare complication.