[Interstitial radiotherapy and prostate cancer. Analysis of the literature. Subcommittee of Prostate Cancer of C.C.A.F.U].

The C.C.A.F.U. reviewed the role of interstitial radiotherapy by analysing 66 references published over the last 10 years, obtained from the Medline database.
Results in Terms of Psa Monitoring: Various modalities of analysis of the laboratory follow-up after radiotherapy have been reported in the literature. The American Society of Therapeutic Radiation Oncology (ASTRO) defines biochemical progression after irradiation by the existence of three consecutive elevations of PSA above the nadir without taking into account the value of this nadir, but the risk of progression appears to continually increase as a function of the PSA nadir; this definition also makes it difficult to compare radiotherapy and surgery. Consequently, we only analysed series reporting results according to strict laboratory criteria (PSAn < or = 1 ng/ml, PSAn < or = 0.5 ng/ml) more than 4 years after treatment. For stage T1-T2 and well differentiated tumours, the 5-year results of interstitial radiotherapy were comparable to those of surgery, and superior to those of external radiotherapy for poorly differentiated tumours. For stage T3 tumours, only 192Ir and, to a lesser extent, 103Pd associated with external irradiation gave slightly better results than those of external irradiation. RESULTS IN TERMS OF FOLLOW-UP BIOPSIES: Post-treatment biopsies may become negative after a considerable period of time, which justifies follow-up biopsies beyond the 24th month. The significance of persistence of tumour cells on the follow-up biopsy is unclear. A correlation between the follow-up biopsy and PSA monitoring has been demonstrated.
Results in Terms of Morbidity: Frequency of early irritating symptoms (45% of cases). Dysuria and retention are frequent late complications, and there is a high risk of incontinence after associated endoscopic resection. The impotence rate is low (25%), but sexual potency decreases with time.
Conclusion: Interstitial radiotherapy can be rightfully considered to be a curative treatment for localized prostate cancer. However, this treatment modality requires further evaluation due to the insufficient follow-up of recent series and the absence of comparative studies.