Stereotactic Body Radiation Therapy (SBRT) is an advanced radiation treatment for prostate cancer. This technique delivers high doses of radiation with pinpoint accuracy to the cancerous prostate in a condensed timeframe, typically over four to five sessions within one to two weeks. Unlike conventional radiation, which involves many smaller daily doses over several weeks, SBRT aims to maximize tumor destruction while minimizing exposure to surrounding healthy tissues. Individuals considering this treatment should understand potential long-term side effects, which can manifest months or even years after treatment.
Long-Term Urinary Complications
Due to the prostate’s proximity to the bladder and urethra, SBRT can cause lasting changes in urinary function. Patients may experience chronic urinary frequency, increased urgency, and nocturia (waking up at night to urinate). Some men might notice a weaker urinary stream or, less commonly, develop stress incontinence, where urine leaks with activities like coughing or sneezing.
These urinary challenges stem from radiation-induced inflammation and scarring of the bladder neck and prostatic urethra. While acute urinary symptoms often improve, some individuals may experience a delayed increase in symptoms, or a “flare,” around 6 to 18 months post-SBRT. Less frequent but more significant complications include urethral strictures, a narrowing of the urethra that can impede urine flow, and chronic hematuria (persistent blood in the urine). These effects highlight the need for ongoing monitoring of urinary health.
Lasting Bowel and Rectal Effects
The rectum lies directly behind the prostate, making it susceptible to radiation exposure during SBRT. A common long-term effect is chronic radiation proctitis, which is inflammation of the rectal lining. This condition can manifest as rectal bleeding, which might range from occasional spotting to more noticeable amounts, and rectal pain or discomfort. Patients may also experience tenesmus, a persistent sensation of needing to pass stool even when the bowel is empty.
Beyond proctitis, SBRT can induce long-term alterations in bowel habits, such as chronic diarrhea or increased urgency. These symptoms generally peak within the first year and often improve over subsequent years. While modern SBRT aims to minimize rectal radiation, some exposure is unavoidable, leading to late effects from damage to the bowel’s delicate lining and small blood vessels.
Changes in Sexual Health
Impact on sexual health is a long-term consideration for men undergoing SBRT. Erectile dysfunction (ED) is a common change, often presenting as a gradual decline in the ability to achieve or maintain an erection sufficient for intercourse. Unlike surgical treatments where ED can be immediate, radiation-induced ED typically develops over months to years, with a decline in sexual function often seen over the first two years post-treatment.
This delayed onset is attributed to slow, progressive damage to the nerves and small blood vessels responsible for erectile function within the pelvic region. Beyond ED, men may experience other changes in sexual health, including decreased ejaculate volume or dry orgasm (orgasm without semen production). These ejaculatory changes are common due to direct irradiation of the prostate and seminal vesicles. Some individuals might also report a decrease in overall sexual desire or libido. The likelihood and severity of these impacts can vary based on a man’s age, pre-treatment sexual function, and overall health status.
Potential Bone and Secondary Cancer Risks
While less common, SBRT carries a potential long-term risk of affecting bone health. One concern is pelvic insufficiency fractures, which can occur in bones like the hip or sacrum within the radiation field. High-dose radiation can weaken bone structure, increasing fracture risk, particularly in older patients or those with pre-existing conditions like osteoporosis. Fractures typically manifest within the first year or two after treatment, with a median time to fracture ranging from 7.5 to 8.4 months.
A very small, but acknowledged, long-term risk of any radiation therapy is secondary cancer development in or near the treated area. This risk generally emerges many years, often decades, after initial treatment. While the overall incidence of radiation-induced secondary cancers remains low, it is a factor discussed as part of the informed consent process for radiation treatments. The benefits of treating the primary cancer typically outweigh this rare risk.
Monitoring and Managing Late Effects
Long-term follow-up appointments with oncology and urology teams are important after SBRT. These regular visits allow healthcare providers to monitor for new or worsening urinary, bowel, or sexual symptoms that may arise months or years after treatment. Patients should openly discuss any changes, as many late effects can be managed effectively.
Various strategies are available to address these effects. For urinary urgency and frequency, medications like alpha-antagonists may be prescribed to relax bladder muscles and improve urine flow. Pelvic floor physical therapy can also strengthen muscles to improve urinary control and reduce discomfort. Rectal bleeding, if it occurs, can often be managed with dietary adjustments or procedures like argon plasma coagulation to seal affected blood vessels. For erectile dysfunction, a range of effective treatments exists, including oral medications, vacuum erection devices, and penile injections.