Present day potentially curative therapies, such as radical prostatectomy and radiation treatment, only make sense as long as the cancer is confined to the prostate and metastases have not developed. Unfortunately, these treatment methods lead in a high percentage of cases to unacceptable and permanent side-effects, e.g. erectile impotency in 60%-100%, rectal disorders in 15% – 40% and urinary incontinence in 10% – 30% of patients. Furthermore, with regard to ‘cure’, the results of treatment by these invasive methods are still unsatisfactory; recurrence rates of between 20% – 50% are reported.
The curative effect of local treatment methods, such as radical operation and radiation therapy, are largely dependent on correct patient selection. Current customary diagnostic procedures, however, often underestimate the extent of the disease, so that patients receiving surgery or radiation treatment are in reality no longer candidates for these methods of treatment, because their prostate cancer has spread from the organ and has already formed micrometastases. There is presently still no cure for metastatic prostate cancer, and the testosterone ablating therapies such as orchidectomy or the administration of LHRH agonists and anti-androgens frequently only achieve short-term tumour control (months to a few years).
Long-term results are unsatisfactory and most prostate cancer patients become hormone refractory. At this stage there is often fast progression of the disease and metastases develop. Various lines of initial treatment, such as newer combinations of chemotherapy, use of radioisotopes (e.g. samarium-153), blocking of growth factors by monoclonal antibodies, immune therapies (e.g. dendritic cell vaccines), angiogenesis blocking strategies, re-differentiation of cancer cells by means of retinoids and vitamin D analogues and finally gene therapy, are presently undergoing clinical trials for this particular situation, but up to now none of these measures has brought patients significant advantages.