ICRP Publication 98: Radiation Aspects of Brachytherapy for Prostate Cancer

ABSTRACT

- The use of permanent radioactive implants (125I or 103Pd seeds) to treat selected localized prostate cancer patients has been rapidly increasing all over the world in the last fifteen years.
To date, it is estimated that more than 50,000 patients are treated this way every year in the world, and this number is anticipated to increase in the near future.
Although no accident or adverse effects involving the medical staff and/or members of the patient family have been reported so far, this brachytherapy technique raises a number of radiation safety issues which need specific recommendations from ICRP.
- All data concerning the dose received by the persons approaching the patients after the implantation have been reviewed. Those doses have been either directly measured or calculated. The available data show that, in the vast majority of cases, the dose to comforters and carers remains well below the 1 mSv/year limit. Only the (rare) case where the patients partner is pregnant at the time of implantation may need specific precautions.
- Expulsion of sources through the urine, the semen or the gastro-instestinal tract is rare.
Specific recommendations should be given to the patient to allow him to deal adequately with this event. Of note, due to the low activity of an isolated seed, and to its low photon energy, no incident/accident linked to a seed loss has ever been recorded.
- Cremation of bodies (frequent in some countries) raises, when it is performed in the first months post-implantation, several issues related to :: 1) the activity which remains in the patients ashes and 2) the airborne dose, potentially inhaled by the crematorium staff or by the members of the public.
Review of available data shows that cremation can be allowed if 12 months have elapsed since an implantation with 125I (3 months for 103Pd). If the patient dies before this delay has elapsed, specific measures must be undertaken.
- Specific recommendations have to be given to the patient to warn his surgeon in case of subsequent pelvic or abdominal surgery. A wallet-card” with all relevant information about the implant is useful.
- In most cases, brachytherapy does make the patient infertile, although the therapy-related modifications of the semen reduce fertility. Patients must be aware of the possibility of fathering children after such a permanent implantation, with a limited risk of genetic effects for the child.
- Patients with permanent implants must be aware of the possibility of triggering certain types of security radiation monitors :: the wallet-card” including the main information about the implant (see above) may prove to be helpful in such a case.
- Considering the available experience after brachytherapy and external irradiation of prostate cancer, the risk of radio-induced secondary tumors appears to be extremely low. The demonstrated benefit of brachytherapy clearly outweighs, by far, the very limited (mainly theoretical) increase of the radiation-induced cancer risk.

Keywords:: radiological protection, I-125, Pd-103, source expulsion, radiation monitors