Brachytherapy for Prostate Cancer: Seed Implants – Complete Guide

What is brachytherapy?

Brachytherapy (also called seed implantation or internal radiation) is a form of radiation therapy where radioactive sources are placed directly inside the prostate. This allows a high dose of radiation to be delivered to the tumour while minimising exposure to surrounding organs (bladder, rectum).

Brachytherapy is an effective curative treatment for low-risk and favorable intermediate-risk prostate cancer. It can be used alone or combined with external beam radiation for higher-risk disease.

LDR brachytherapy (permanent seeds)

Low-dose-rate (LDR) brachytherapy uses permanent radioactive seeds implanted into the prostate. The seeds remain in place permanently but become inactive over time.

Radioactive isotopes:

• Iodine-125 (I-125): Half-life 60 days – most common
• Palladium-103 (Pd-103): Half-life 17 days – faster decay
• Cesium-131 (Cs-131): Half-life 9.7 days – newest, very short half-life

Procedure:

• 60-120 seeds are implanted through needles placed via the perineum
• Ultrasound guidance ensures precise placement
• Procedure takes 1-2 hours
• Seeds are permanent (not removed)
• Radiation is delivered over weeks to months (until seeds decay)

Advantages:

• One-time procedure (no daily treatments)
• Convenient (outpatient or 23-hour stay)
• Excellent cancer control for low-risk disease

HDR brachytherapy (temporary)

High-dose-rate (HDR) brachytherapy uses a temporary radioactive source that is inserted for a few minutes and then removed. Multiple treatments are given over 1-2 weeks.

Procedure:

• Hollow catheters are placed into the prostate through the perineum
• A remote-controlled machine (afterloader) sends a radioactive source into the catheters
• Treatment takes 10-20 minutes per session
• Catheters are removed after the final treatment
• Typically 1-4 treatments (1-2 fractions)

Advantages:

• No permanent seeds (no radiation precautions)
• Can be combined with external beam radiation for higher-risk disease
• Excellent dose distribution

Disadvantages:

• Requires multiple procedures (catheter placement each time)
• More invasive than LDR

Who is a candidate for brachytherapy?

Ideal candidates for brachytherapy (especially LDR monotherapy) meet the following criteria:

• Low-risk prostate cancer: Gleason 6 (3+3), PSA <10, T1-T2a
• Favorable intermediate-risk (select patients): Gleason 3+4=7, low volume of pattern 4
• Prostate size <60 mL: Smaller prostates are easier to implant
• Good urinary function: No severe baseline urinary symptoms (IPSS <15-20)
• No prior TURP: Previous prostate surgery increases complication risk

Contraindications:

• Large prostate (>60-80 mL) – may require hormone therapy to shrink before brachytherapy
• Severe urinary symptoms (IPSS >20)
• Prior pelvic radiation
• Large median lobe (difficult to implant)

The brachytherapy procedure – seed placement

Before the procedure:

• Transrectal ultrasound (TRUS) to map the prostate
• Treatment planning (1-2 weeks before)
• Stop blood thinners
• Antibiotics to prevent infection
• Bowel preparation (enema)

Day of procedure (LDR):

• Anaesthesia: Spinal or general anaesthesia
• Duration: 1-2 hours
• Hospital stay: Outpatient or 23-hour stay

Step-by-step:

1. You are positioned on your back with legs elevated (lithotomy position)
2. An ultrasound probe is inserted into the rectum to visualise the prostate
3. A template grid is placed against the perineum (skin between scrotum and anus)
4. Needles are inserted through the grid into the prostate
5. Radioactive seeds are deposited through the needles
6. Needles are removed
7. A cystoscope is inserted to check for seeds in the bladder
8. A urinary catheter may be placed (temporary)

Recovery and side effects – urinary symptoms, radiation precautions

Urinary side effects (most common):

• Frequency and urgency: Very common – peaks at 1-3 months, resolves by 6-12 months
• Dysuria (painful urination): Common – treat with urinary analgesics (phenazopyridine)
• Hematuria (blood in urine): Mild, resolves in days
• Urinary retention: 5-10% require temporary catheter for 1-4 weeks
• Late effects: Urethral stricture (rare, 2-5%)

Bowel side effects (less common):

• Mild diarrhoea, rectal urgency – less than external beam radiation
• Rectal bleeding (proctitis) – 2-5%, usually mild

Radiation precautions (LDR only):

• Seeds emit low-dose radiation for weeks to months
• Limit close contact with pregnant women and children: Avoid holding children on lap for 2 months
• Sleep in separate bed from pregnant partner: For 2 months (I-125) or 1 month (Pd-103)
• No special precautions needed for adults – radiation exposure is very low
• Seeds may be seen on airport security scanners (carry a card from your doctor)

Success rates – excellent for low-risk cancer

Brachytherapy has excellent cancer control outcomes, especially for low-risk disease:

• Low-risk (Gleason 6): 10-year biochemical recurrence-free survival: 85-95%
• Favorable intermediate-risk (Gleason 3+4=7): 10-year biochemical recurrence-free survival: 80-90%
• Unfavorable intermediate-risk (Gleason 4+3=7) – with EBRT boost: 10-year biochemical recurrence-free survival: 75-85%

PSA nadir after brachytherapy:

• PSA declines slowly over 18-36 months
• Nadir (lowest PSA) should be <0.5 ng/mL
• PSA bounce (temporary rise) occurs in 30-40% of men at 1-2 years – does not indicate recurrence

Brachytherapy vs. external beam radiation – comparison

Feature	LDR Brachytherapy	External Beam (IMRT/SBRT)
Convenience	One-time procedure (1-2 hours)	8-9 weeks daily (or 5 SBRT treatments)
Catheter	1-3 days (temporary)	None
Urinary side effects	More common (frequency, urgency, retention)	Less common
Bowel side effects	Less common	More common (diarrhoea, rectal bleeding)
Erectile dysfunction	20-40% at 5 years	20-40% at 5 years
Radiation precautions	Yes (LDR only – 1-2 months)	No
Best for	Low-risk, favorable intermediate-risk	All risk groups (with hormone therapy for high-risk)

Interactive FAQ – Brachytherapy for prostate cancer

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Disclaimer: This information is for educational purposes. Brachytherapy decisions should be made with a radiation oncologist. Consult a specialist at Vivekananda Hospital for personalised treatment recommendations.