Brachytherapy

What is brachytherapy?

Brachytherapy literally means ‘short therapy’. There are two types of prostate brachytherapy: low dose-rate (LDR) and high dose-rate (HDR). (The term ‘dose-rate’ refers to the speed of radiation source used and not to the actual radiation dose or level delivered.) Low dose-rate is most commonly used.

Who is suitable for brachytherapy?

This treatment is only suitable for those whose prostates are not over-enlarged and for those who have few, or mild, urinary symptoms. Typically men with low- or intermediate-risk prostate cancers are treated with LDR seed implant alone. Such patients would normally have a PSA below 15, a Gleason score no more than 6 or 7, and a cancer stage of T2b or less. Where there is a possibility of spread, or for higher-risk disease, a short course of radiotherapy and/or Hormone treatment is sometimes offered.

HDR Brachytherapy is normally given with a short external beam radiotherapy course and is more suited to men with a higher-risk cancer which may have spread to the seminal vesicles i.e. stage T3b, Gleason 8–10.

Low dose-rate Brachytherapy (LDR)

Low dose-rate Brachytherapy, unlike External Beam Radiation Therapy, treats the cancer by permanently inserting tiny radioactive seeds of Iodine-125 into the prostate with the aim of destroying the cancer.

What is involved?

The process is done in two or three visits:

1) An outpatient appointment will assess your suitability for the treatment, and will consist of some simple tests, which would typically include a DRE examination and a trans-rectal ultrasound examination.

2) The first stage of the treatment will be done as a day case in order to identify the exact size and shape of the prostate by computer imaging, and to plan the radiation dosage required.

3) The second stage of the treatment consists of the actual implantation of the seeds under general anaesthetic by a series of 20–30 needles,each implanting between 2 and 6 seeds. X-rays may be taken during the procedure. You will wake with a catheter in place, which is removed before you leave hospital. A CT scan may be done following the treatment in order to check that the right dose has been delivered. Patients are sent home the next day with antibiotics and other medicines.

Most centres now would combine stages 2 and 3 in one visit. Some centres offer a ‘brachy boost’ whereby low dose-rate brachytherapy is combined with a course of external beam radiation.

Is the radiation dosage dangerous?

The major portion of the radiation is released from the seeds into the prostate over the first three months. Thereafter the radiation decreases so that it is negligible after nine months. While the seeds are radioactive, you are not. No special precautions are generally considered necessary, but it is suggested that you avoid near contact with pregnant women, and young children should not sit on your lap for the first two months after the treatment. When having intercourse, you may be advised to use condoms for the first two occasions, to avoid the risk of passing a radioactive seed.

High dose-rate Brachytherapy (HDR)

Sometimes called temporary Brachtherapy, is suited for both early-stage and some locally-advanced prostate cancers (up to stage T3b). It is used in conjunction with external beam radiotherapy and/or Hormone treatment. In some instances, HDR Brachytherapy may be used as a sole treatment.

How does High dose-rate differ from Low dose-rate?

HDR Brachytherapy involves the insertion of a radioactive bead into tiny plastic rods which are temporarily placed into the prostate to deliver the appropriate dose (as opposed to low dose-rate, in which the seeds are permanently implanted). 15–20 of these thin, hollow rods are placed into the gland through the perineal area with the aid of a template, through which an iridium bead is inserted. A computer-controlled machine pushes the beads into the rods one by one. It also controls the length of time the radiation is given through the rods.

At the end of the treatment the rods are withdrawn, with no radioactive material remaining in the prostate. If combined with External Beam Radiation Therapy, it is usually performed first, and the radiation follows approximately two weeks later. Results for High dose-rate Brachytherapy are similar to those for Low dose-rate treatment.

Men with low- or intermediate-risk
prostate cancer are treated with LDR.

HDR Brachytherapy is normally given
with a short External Beam Radiotherapy
course and is more suited to men with
a higher-risk cancer.

How will I know whether the treatment has been successful?

As with any radiotherapy treatment, the potential success of Brachytherapy will not be known until about 36 months after the treatment has finished, when the PSA will have reached its lowest level. If there is a steady rise of more than 2.0ng/mL above this low point in a six-month period, your consultant should be advised.

Side effects

About 5–10% of patients may experience temporary urinary retention. Some may experience frequency and urgency, which are again generally temporary. Bowel problems (constipation or frequency) can occur 3–6 months after the treatment. Erectile problems can occur in up to 20–30% of men. These risks are claimed to be lower than with surgery or external beam radiotherapy and it has been shown that they have significantly improved with greater experience. There is evidence of a small risk of pelvic cancers after Brachytherapy.

4D Brachytherapy

A newer method becoming more common in many hospitals is 4D Brachytherapy. It only requires two visits – an initial outpatient assessment, followed by the seed implantation, during which the planning is performed, known as real-time planning. 4D Brachytherapy uses two different types of seeds which come ready prepared in the correct implantation order. The whole procedure can be done more efficiently and accurately in under an hour, with a quicker recovery time and with fewer side effects for the patient.