Prophylactic brachytherapy.

Prostate cancer is together with the carcinoma of the lung the most common cancer in the western world. Better screening methods especially the introduction of PSA (prostate specific antigen) in the beginning of the 90's has increased the early detection rate. In the United States only 30% of prostate tumors were in their early stages before the introduction of PSA-screening as compared to 60% nowadays. The early detection also increased the rate of younger men amongst these patients. Patient demands have increased with respect to incontinence and impotence especially amongst those young patients. Radical prostatectomy still is the gold standard for therapy of localized prostate cancer. Better operating techniques have decreased the side effect rate of this operations but many patients still do not undergo this operation because they fear these side effects. Originating from the USA the low dose rate brachytherapy (LDR) using permanent seeds had a renaissance in recent years. In 1999 alone more than 40,000 patients were successfully operated using this technique. 10 year data published in 1998 showed similar results as compared to a multitude of radical prostatectomy studies and superior results to most of the published external beam studies with significantly less side effects. In Germany and western Europe more and more centers start with LDR-brachytherapy. In contrary to the U.S. where brachytherapy is mostly performed as an outpatient procedure, nearly all European centers do only inpatient brachytherapy. Only very few centers perform outpatient procedures; the first results are very encouraging showing few complications and a very high standard of quality of the treatment.

Brachytherapy↗

PubMed2001

[Physical brachytherapy planning].

The treatment of prostate cancer, confined to the gland, with high conformal doses to the target volume and sparing of bladder, rectum and urethra at the same time can be achieved by interstitial brachytherapy. Close cooperation of urologist and radiologist, together with the physical treatment planning have improved the clinical results significantly. The ongoing development of new radioactive isotopes and of dedicated computerized treatment planning systems have resulted in a renaissance of the interstitial treatment. "Preplanning" i.e. preoperative treatment planning can be performed precisely and fast. Improved ultrasound techniques allow during the perineal template guided seed implantation a realtime dose calculation resulting in an improved seed placement. CT- or MRI based "postplanning" guarantees for early postoperative dose documentation and quality assurance. 2-dimensional as well as 3-dimensional dose distributions superposed to anatomical structures and dose volume histograms (DVH) allow for dose optimization and quality decision. 192Ir with high activity is used for the high dose rate (HDR) afterloading treatment as a boost after external radiotherapy. 125I and 103Pd as well are used as permanent implants to boost external irradiation. If fast growing low grade tumors should be treated with 103Pd permanent implant and slow growing tumors with 125I is discussed controversialy. About 50 to 100 seeds are implanted. The implanted patients are allowed to leave the hospital as there is sufficient shielding by the surrounding normal tissue. Postplanning is based on CT- or MRI for dose documentation and quality assurance. For 125I treatments the activity-dose-relation was redefined since 1995 (TG43 protocol). Similar corrections seem to be necessary for 103Pd treatments.

Brachytherapy↗