Permanent seed brachytherapy for prostate cancer is one of the most advanced forms of localized radiation therapy, delivering high precision and direct tumor targeting within the prostate. The technique involves implanting tiny radioactive seeds that continuously release a low dose of radiation, effectively eliminating cancer cells while protecting nearby healthy tissue. This treatment is especially suitable for patients with low- to intermediate-risk prostate cancer, offering strong therapeutic outcomes with minimal side effects.
What are permanent prostate seeds?
Permanent prostate seeds are small cylindrical pellets, roughly the size of a grain of rice, containing low-energy radioactive isotopes such as:
- Iodine-125 (I-125): Emits low-energy radiation with limited spread, gradually delivering the dose over several months.
- Palladium-103 (Pd-103): Slightly higher energy with a faster radiation effect, ideal for smaller tumors.
These pellets are implanted directly into the prostate, creating a concentrated radiation dose within the tumor that rapidly diminishes beyond the prostate boundaries. This targeted approach minimizes exposure to nearby healthy tissues such as the rectum and bladder.
Benefits of permanent prostate seeds
Compared to other treatment options, permanent seed brachytherapy for prostate cancer offers several advantages:
- High therapeutic effectiveness
- Less invasive than surgery
- Better preservation of sexual function compared to surgery
- Reduced exposure to surrounding vital organs (bladder and rectum)
- Short recovery time, as most patients return to daily life within a few days
Permanent seed brachytherapy for prostate cancer can also be combined with external beam radiation therapy (EBRT) to enhance treatment effectiveness. The following table outlines the key differences between the two approaches:
| Criteria | Permanent Prostate Seeds | External Beam Radiation Therapy (EBRT) |
|---|---|---|
| Mechanism | Implantation of small radioactive pellets directly into the prostate, where they remain permanently and gradually release radiation | High-energy beams directed from outside the body toward the prostate over multiple sessions |
| Number of sessions | Typically, a single procedure; radiation continues automatically for several months | Multiple daily sessions (usually 5 days a week for 4–8 weeks) |
| Dose concentration | Highly concentrated dose within the prostate, minimal exposure to surrounding tissue | Dose distributed across the prostate and nearby organs, with some exposure to the bladder and rectum |
| Impact on surrounding organs | Very limited due to internal dose distribution | Relatively higher, with increased risk of urinary and bowel side effects |
| Recovery time | Relatively short, most patients resume normal activities within days | Longer, typically after completing the full course of sessions |
| Common side effects | Temporary urinary irritation, incontinence, and occasional erectile dysfunction | Urinary and bowel irritation, fatigue, and occasional erectile dysfunction |
| Patient suitability | Low- to intermediate-risk prostate cancer with suitable prostate size | All stages of the disease, especially intermediate to high-risk cases, or when implantation is not feasible |
| Treatment effectiveness | Very high, especially in carefully selected patients | High, particularly when combined with hormone therapy for high-risk cases |
When is permanent seed brachytherapy for prostate cancer recommended?
Permanent seed brachytherapy for prostate cancer is typically advised in cases of:
- Low to intermediate-risk prostate cancer, characterized by:
- Gleason score ≤ 7
- PSA level < 20 ng/mL
- Tumor confined within the prostate gland (T1–T2)
- Patients who prefer to avoid surgery or have medical contraindications to surgical procedures
- Therapeutic goals:
- Maintaining urinary control
- Minimizing the impact of treatment on sexual function
- Achieving high local efficacy with minimal surgical intervention
Permanent seed brachytherapy for prostate cancer procedure
To ensure optimal outcomes, several steps must be followed:
Patient evaluation before permanent seed brachytherapy for prostate cancer procedure
Before proceeding with permanent seed brachytherapy for prostate cancer procedure, a comprehensive assessment is required:
- Medical history and clinical examination:
- PSA level measurement
- Evaluation of prostate size and urinary tract condition
- Imaging studies:
- MRI: For precise tumor boundary identification and dose planning
- Transrectal ultrasound: To estimate prostate volume and guide seed placement
- Functional assessment of urinary and sexual health:
- Urine flow and continence evaluation
- Assessment of erectile function to anticipate potential side effects
- Radiation Planning:
- A 3D-based planning is used to optimally distribute the dose and avoid overexposure to the bladder or rectum
- A detailed treatment plan is created using specialized software to determine the exact number and placement of seeds within the prostate
- The goal is to ensure complete coverage of the tumor with an adequate radiation dose while keeping the surrounding healthy tissue within safe limits
Steps of permanent seed brachytherapy for prostate cancer
The implantation procedure typically includes the following stages:
Anesthesia
The patient usually receives spinal (lower back) anesthesia, though general anesthesia may be used if the patient’s health status or the physician’s recommendation indicates it. The patient is positioned on their back with legs elevated to allow access to the perineal area (between the scrotum and anus). A urinary catheter is inserted to empty the bladder, and a transrectal ultrasound is performed to assess prostate size and shape accurately. This data is used to generate a 3D-based electronic implantation plan.
Guidance techniques
Before needle insertion, a medical physicist prepares a digital treatment plan showing the distribution of seeds within the prostate to ensure complete radiation coverage. Transrectal ultrasound serves as the primary guidance tool during the procedure, providing cross-sectional images that help the physician determine the correct angle and depth for each needle. The ultrasound probe is fixed in place, and a grid with numbered holes is used to guide needle placement precisely according to the treatment plan.
Seed implantation
Thin stainless steel needles are inserted through the perineal skin into the prostate tissue under ultrasound guidance. The radioactive seeds are delivered through these needles and placed at predetermined locations according to the 3D plan. Typically, 60 to 120 rice-sized seeds are implanted and evenly distributed to cover the entire prostate. In some centers, fine threads or small carriers are used to link groups of seeds together to stabilize their position post-implantation. Once the procedure is complete, the needles are carefully withdrawn without disturbing the seeds, and light pressure is applied to the area to reduce the risk of bleeding or hematoma.
Immediate evaluation
After implantation, X-ray or CT imaging is performed either in the operating room or a few hours later to confirm the exact distribution and positioning of the seeds within the prostate. This evaluation ensures that the radiation dose adequately covers the gland as planned. Any small imbalances in the distribution can be detected and corrected early. The number and location of the seeds are recorded for future monitoring and to ensure radiation safety. The patient typically remains under observation for a few hours and is then discharged from the hospital the same day or the following day.
Follow-Up After Permanent Prostate Seed Therapy
To achieve the best possible outcomes, it is important to follow several key steps:
- Imaging studies: Performed as needed to assess seed placement and distribution
- Regular PSA testing: To monitor treatment success and detect any potential recurrence
- Clinical evaluation: Ongoing assessment of urinary and sexual symptoms, with supportive treatment adjustments as necessary
- Recommended follow-up schedule:
- Every 3–6 months during the first two years
- Annually thereafter, or as advised by the treating physician
Potential complications of permanent seed brachytherapy for prostate cancer
Although permanent radioactive seed implantation is considered a safe and effective treatment for low- to intermediate-risk prostate cancer, it may lead to certain side effects and complications. These vary in severity and duration from one patient to another. Most are temporary and improve over time with conservative management. Common complications include:
Urinary Complications
- Urinary complications:
- Temporary urinary retention: Swelling of the prostate after the procedure may cause partial blockage of the urinary tract.
- Difficulty urinating: Patients may experience a burning sensation during urination due to irritation of the urethra and bladder from radiation. This typically appears within the first few weeks after implantation and is treated with anti-inflammatory medications and diuretics.
- Frequent urination or bladder irritation: The localized radiation dose can increase bladder wall sensitivity, leading to frequent urges to urinate. These symptoms usually improve gradually over 3–6 months.
- Bowel complications:
- Mild rectal bleeding: Mild bleeding from the anus may occur weeks after implantation due to radiation affecting small blood vessels in the rectal wall near the prostate.
- Rectal irritation or temporary diarrhea: Patients may experience a burning sensation, mild diarrhea, or frequent urges to defecate due to minor radiation exposure of the rectum.
- Sexual complications:
- Erectile dysfunction: Continuous radiation from the seeds may gradually affect the nerves responsible for erection. This issue tends to develop over months to years following treatment.
- Reduced sexual desire: Some patients may notice a temporary drop in libido, often linked to psychological stress or anxiety rather than the radiation itself.
- Rare side effects:
- Infection at the implantation site: Rarely, a localized infection may occur at the needle entry sites in the prostate or the surrounding skin. Preventive antibiotics are typically used, and infections are usually easy to treat.
- Seed migration outside the prostate: Occasionally, some radioactive seeds may migrate to other areas, such as the lungs or bladder. However, this rarely causes clinical harm and is usually detected through follow-up imaging.
Post-Procedure Instructions After Permanent Prostate Seed Implantation
After returning home, patients are advised to follow these guidelines:
- Avoid prolonged sitting on hard surfaces
- Drink plenty of water during the first few days
- Refrain from strenuous physical activity or heavy lifting for about a week
- Use condoms during sexual intercourse in the first few weeks to prevent the potential release of a radioactive seed
- Avoid extended close contact with pregnant women and young children during the initial weeks, until the radioactive activity gradually diminishes
Permanent seed brachytherapy for prostate cancer is a safe and highly effective treatment for early-stage cases, offering high cure rates while preserving overall quality of life. While some urinary or bowel side effects may occur, they are generally mild, temporary, and manageable. The long-term success of this therapy depends on precise planning, accurate implementation, and consistent follow-up after the procedure to ensure optimal outcomes.
Sources:
- Prostate Cancer UK. (2022, October). Permanent seed brachytherapy.
- Cancer Research UK. (2025, July 2). Permanent seed brachytherapy for prostate cancer.
