In brachytherapy, the radioactive source is implanted directly into the prostate. This involves a number of advantages compared to external radiation treatment.
Benefits compared to external radiation treatment
- Problem with positioning of patient and organ movement is eliminated.
- Allows increased dosing to the target volume and thereby possible increase in curative potential.
- Shorter treatment time
- Saves normal tissue structures (especially rectum and bladder)
Disadvantages of brachytherapy
- Invasive procedure with the need for anesthesia
- Over dosing of urethra (the apex-region)
- Obesity can cause technical problems
- Increase in risk for complications in diabetes and symptom-causing arteriosclerosis in the pelvis
- Risk of underdosage outside the prostate gland
To ensure the irradiation of possible microscopic cancer outside the prostate capsule, brachytherapy is always given combined with conformal (organ configured) external radiation therapy.
We destinguish between high-dose (HDR) and low-dose (LDR) brachytherapy. In HDR, a boost dose is given with iridium 192 before external radiation therapy. The radiation sources are implanted transperineally. In LDR, the seeds are implanted with iridium 131 permanently in the prostate. Theoretically, there is a great difference between these two methods for administration of brachytherapy. The practical implication of this is uncertain.
It can be appropriate to give hormone treatment in addition to the radiation therapy in patients where:
- The volume of the prostate is large (< 60 cc)
- The tumor has grown through the capsule (T3 and/or serum-PSA > 20 ng/ml and/pr Gleason score ≥ 8
- T1/T2 pN0, PSA ≥ 20
- T1/T2 pN0, Gleason score ≥ 8
- T2 pN0, 20 < PSA < 70
- T3 pN0, PSA < 70
- Obstructive symptoms from the urinary tract
- IPSS > 12 (significant urine retention)
- Pathology in urethra (tumor breakthrough, stenosis/strictures)
- Infiltration to tthe rectum and/or seminal vesicles
- TUR-P < 6 months or large cavity
- Large adenoma in the prostate (lobus tertius)
- Large volume > 60 cc (many needles, os pubis)
- A lot of prostate calcification
- Serum PSA > 50
- Previous rectal amputation