Brachytherapy, a form of internal radiation, is a highly effective treatment option for prostate cancer, particularly for localized disease. The procedure involves placing sealed radioactive sources directly into the prostate gland. This allows for the delivery of a high dose of radiation precisely to the tumor while minimizing exposure to surrounding healthy tissue. Success is determined by factors including the cancer’s stage and aggressiveness, the patient’s health, and the specific technique used. This internal approach provides long-term cancer control rates comparable to surgery or external beam radiation therapy.
The Two Methods of Brachytherapy
The treatment is categorized into two main delivery methods, distinguished by the rate at which radiation is delivered: Low-Dose Rate (LDR) and High-Dose Rate (HDR) brachytherapy. The key difference is whether the radioactive source is left in the body permanently or used temporarily.
Low-Dose Rate (LDR) Brachytherapy
LDR brachytherapy, also known as permanent seed implantation, involves placing many tiny, rice-grain-sized radioactive seeds directly into the prostate gland. These seeds, often containing Iodine-125 or Palladium-103, emit radiation slowly over several months before decaying to an inactive state, remaining permanently in the tissue. This procedure is completed in a single session, often on an outpatient basis.
High-Dose Rate (HDR) Brachytherapy
HDR brachytherapy uses thin, hollow needles or catheters temporarily inserted into the prostate to deliver a concentrated dose of radiation. A powerful radioactive source, such as Iridium-192, is guided through these catheters for a few minutes at a time before being retracted and removed. The total radiation dose is divided into multiple treatment sessions, or fractions, over one or two days, and the catheters are removed once the full dose has been delivered.
Measuring Treatment Success
Treatment success is commonly measured by the rate of Biochemical Recurrence-Free Survival (BRFS). This metric refers to the percentage of men whose Prostate-Specific Antigen (PSA) level remains low and stable, indicating that the cancer has not returned. Long-term data confirms brachytherapy’s effectiveness, particularly for men with lower-risk disease.
For men with low-risk prostate cancer, brachytherapy alone (monotherapy) yields excellent long-term results, with 10-year BRFS rates often exceeding 90%. Intermediate-risk patients also show high success rates with monotherapy, reporting 15-year BRFS rates around 84% to 85%. These outcomes are comparable to radical prostatectomy or external beam radiation therapy alone.
In cases of higher-risk or more aggressive disease, brachytherapy is combined with other therapies to maximize cancer control. Combining a brachytherapy boost (LDR or HDR) with External Beam Radiation Therapy (EBRT) and hormone therapy has proven highly effective. Studies show that this combined approach significantly improves recurrence-free survival compared to dose-escalated EBRT alone. For intermediate- and high-risk patients, the recurrence-free survival rate at 9 years was approximately 83% when receiving the LDR boost and EBRT combination, compared to 62% for those receiving only dose-escalated EBRT. For high-risk disease, the combination approach with HDR brachytherapy and EBRT can achieve disease-free survival rates of 80% or higher.
Patient Suitability and Selection
Determining the ideal candidate for brachytherapy requires assessing several pre-treatment factors to maximize success. The treatment is most effective when the cancer is confined to the prostate gland (localized disease).
Clinical Factors
Specific clinical factors, such as the initial Prostate-Specific Antigen (PSA) level, play a significant role in selection. A PSA level of 10 ng/mL or less is often considered favorable for LDR brachytherapy monotherapy. The Gleason Score, which measures cancer aggressiveness, is also important; scores of 6 or 7 often indicate suitability for brachytherapy alone. Patients with higher scores usually receive brachytherapy combined with external beam radiation and hormone therapy. Clinical T-stage, describing the tumor extent, should ideally be T1c or T2a, meaning the cancer is relatively small and has not spread significantly beyond the prostate capsule.
Physical Factors
The physical characteristics of the prostate gland also influence suitability. An ideal prostate size for seed implantation is less than 50 cubic centimeters. For larger glands, a short course of hormone therapy may be used to shrink the prostate before the procedure. Pre-existing urinary symptoms are also considered, as significant urinary blockages or poor flow may increase the risk of post-treatment side effects.
Potential Treatment Side Effects
Brachytherapy carries a risk of side effects, categorized as acute (short-term) or chronic (long-term). Acute side effects are temporary and often involve urinary tract irritation in the weeks following the procedure. Symptoms include increased urinary frequency, urgency, and a burning sensation during urination, which typically resolve within several months as swelling subsides.
Long-term side effects can affect the urinary, bowel, and sexual systems, though severe complications are uncommon. Chronic urinary issues may include persistent frequency or urgency, and rarely, a narrowing of the urethra (stricture) may occur. Urinary incontinence is possible but generally mild, and is more likely if a patient has had previous prostate surgery.
Bowel-related complications are less frequent than with external beam radiation, as the localized dose largely spares the rectum. These may include radiation proctitis, which is inflammation of the rectal lining causing bleeding, mild pain, or increased bowel movements. The impact on sexual function is a common concern, with erectile dysfunction being a potential long-term side effect.