Brachytherapy is a form of internal radiation therapy that treats prostate cancer by placing radioactive sources directly inside or next to the prostate gland. Unlike external beam radiation, which aims beams from outside the body, brachytherapy delivers a concentrated dose right at the tumor while limiting exposure to surrounding healthy tissue. It’s used as a primary treatment for early-stage prostate cancer and sometimes combined with external radiation for more aggressive cases.
How Brachytherapy Works
The basic idea is straightforward: get the radiation as close to the cancer as possible. During the procedure, a doctor uses ultrasound imaging to guide needles through the perineum (the skin between the scrotum and anus) and into the prostate. Those needles deliver radioactive material to precise locations within the gland. You’re under anesthesia for the entire procedure and won’t feel pain.
The radiation damages the DNA of cancer cells, preventing them from dividing and growing. Because the source sits inside the prostate itself, the radiation travels only a short distance. This means the bladder, rectum, and other nearby structures receive far less radiation than they would with external beam therapy alone.
LDR vs. HDR: Two Different Approaches
There are two types of prostate brachytherapy, and the key difference is how long the radioactive material stays in your body.
Low-dose rate (LDR) brachytherapy uses tiny radioactive seeds, each about the size of a grain of rice, that are permanently implanted in the prostate. A doctor places dozens of these seeds using a needle guided by ultrasound. The seeds emit low levels of radiation over weeks to months, gradually losing their radioactivity. They stay in the prostate permanently but become inert once they’ve delivered their full dose. The procedure itself is typically done in a single session.
High-dose rate (HDR) brachytherapy takes a temporary approach. Thin tubes called catheters are inserted into the prostate at precise locations, and a single high-intensity radioactive source travels through those tubes using a computer-controlled device called a remote afterloader. The source stays in each position for just a few minutes before being withdrawn. Nothing radioactive remains in your body afterward. HDR is often delivered in one to several sessions and is frequently combined with a shorter course of external beam radiation.
Who Is a Good Candidate
Brachytherapy works best when the cancer is still confined to the prostate. Doctors evaluate candidacy based on three main factors: the clinical stage of the tumor, the Gleason score (a measure of how aggressive the cancer cells look under a microscope), and the PSA level in your blood.
For LDR brachytherapy as a standalone treatment, ideal candidates typically fall into the low-risk category: a clinical stage of T1a through T2b, a Gleason score of 6 or less, and a PSA of 10 or less. Men with intermediate-risk disease, where one of those values is higher (a Gleason score of 7, a PSA above 10, or a slightly more advanced stage), may still be candidates but often receive brachytherapy combined with external radiation or a short course of hormone therapy.
High-risk patients, those with two or more unfavorable factors, are more likely to receive HDR brachytherapy as a boost alongside external beam radiation rather than brachytherapy alone. Prostate size also matters. When the gland exceeds about 60 cubic centimeters in volume, the pubic bone can physically block the needles from reaching parts of the prostate. In those cases, hormone therapy to shrink the gland may be used first, or a different treatment approach may be recommended.
What the Procedure Feels Like
For LDR brachytherapy, you’ll likely go home the same day or the following morning. The procedure itself takes one to two hours. An ultrasound probe is placed in the rectum to create a live image of the prostate, and the doctor uses that image to guide a needle through the perineum. The needle places the radioactive seeds at mapped-out positions throughout the gland. Because you’re under anesthesia, you won’t feel the needle insertions.
HDR brachytherapy involves a similar setup for catheter placement. Once the catheters are in position and you’ve recovered from anesthesia, you’re connected to the afterloader machine, which sends the radioactive source through each catheter according to a computer-generated plan. Each treatment session lasts only minutes. Depending on the protocol, you may have the catheters in place for one session or return for a second session before they’re removed.
Side Effects to Expect
The most common side effects involve urination. In the weeks following seed implantation, many men experience urinary frequency, urgency, a weak stream, or a burning sensation when urinating. This happens because the seeds and the swelling from the procedure sit right next to the urethra, which runs through the center of the prostate. These symptoms typically peak in the first one to three months and gradually improve over the following months as inflammation subsides and, in the case of LDR, the seeds lose their radioactivity.
Bowel irritation is less common but can include rectal discomfort, looser stools, or occasional urgency. These symptoms tend to be milder than those caused by external beam radiation because less radiation reaches the rectum.
Erectile dysfunction is a concern with any prostate cancer treatment. With brachytherapy, the risk is generally lower than with surgery, but it increases over time. Many men maintain erectile function in the first year or two, with gradual changes developing later. The likelihood depends on your age, baseline function before treatment, and whether brachytherapy is combined with hormone therapy or external radiation.
Urinary incontinence, the involuntary leakage that many men fear, is relatively uncommon after brachytherapy compared to surgical removal of the prostate. Most men retain normal urinary control.
How Well It Works
Brachytherapy has strong long-term outcomes, particularly for low- and intermediate-risk prostate cancer. For low-risk disease treated with LDR brachytherapy alone, cancer control rates at 10 years are consistently high across major cancer centers, often exceeding 90%.
For high-risk disease, combining HDR brachytherapy with external beam radiation produces notably better results than external radiation alone. A study published in Radiotherapy and Oncology found that 10-year prostate cancer-specific mortality was just 2.5% with the combination approach, compared to 8.2% with external radiation only. Overall mortality at 10 years was 16% versus 23%. That’s a meaningful difference, particularly for men who are younger at diagnosis and have decades of life ahead.
These outcomes are broadly comparable to radical prostatectomy (surgical removal of the prostate) for similar risk categories, which is why brachytherapy is considered a standard curative option rather than a lesser alternative to surgery.
Radiation Safety After Treatment
If you have HDR brachytherapy, there are no radiation precautions after the procedure because the source is removed completely. You pose no risk to anyone around you.
LDR brachytherapy is different. The seeds remain in your prostate and emit low-level radiation for several months. The radiation doesn’t travel far, so normal daily interactions with adults are safe. However, most treatment centers recommend limiting prolonged close contact with pregnant women and young children for the first two months or so. This typically means avoiding having a small child sit in your lap for extended periods. Your radiation oncologist will give you a specific timeline based on the type of seeds used. After several months, the seeds become completely inactive and no precautions are needed.
Rarely, a seed can be passed during urination. If this happens, you’ll be advised not to handle it with bare hands and to contact your treatment team for disposal instructions.
Recovery Timeline
Most men return to normal daily activities within a few days of either type of brachytherapy. Heavy lifting and strenuous exercise are typically avoided for a week or two to allow the perineal area to heal. Urinary symptoms are usually the main inconvenience during recovery, and your doctor may prescribe medication to relax the bladder and ease the flow of urine.
Follow-up involves regular PSA blood tests, usually every three to six months in the first few years, then annually. After brachytherapy, PSA levels decline slowly over 12 to 24 months. A temporary rise in PSA, sometimes called a “PSA bounce,” can occur in the first two years and doesn’t necessarily signal a recurrence. Your oncologist will track the overall trend rather than reacting to any single reading.