[Usefulness and positioning of MAB therapy for prostate cancer]

Prostate cancer is a relatively slow-growing disease compared to other cancers, and the patients tend to be older. Taking into consideration therefore life expectancy of the patients and risks of recurrence and progression, conservative treatments (mainly hormonal therapy) are often applied for early cases, as well as radical treatments (total prostatectomy and radiotherapy). Particularly in Japan, many patients start treatment with hormonal therapy alone, in both early and advanced cases. Hence, Maximal Androgen Blockade (MAB) therapy, in which surgical or medical castration (such as LH-RH agonist treatment) and anti-androgen treatment are combined, is widely exercised with the hope to enhance treatment effects. The usefulness of MAB therapy has been assessed in a number of randomized comparative studies, covering mainly metastatic cases. The efficacy of the therapy with the use of flutamide as non-steroidal anti-androgen has been confirmed in some of the studies, although the magnitude of the efficacy cannot be said major. In Phase III clinical studies of MAB therapy with bicalutamide being conducted in Japan for patients in Stages C and D, however, the patient group treated with MAB therapy demonstrated more favorable results compared to the group treated with LH-RH agonist alone, particularly in terms of time to progression (TTP) of the patients in Stage C. These are relatively new findings on the usefulness and adaptability of MAB therapy. In this Panel Discussion, views and experiences are exchanged on a wide variety of topics covering the real usefulness of MAB therapy, its adaptability, possible outcomes of hormonal therapy in early cases, and the future of MAB therapy, taking into account the prevailing opinions and current practices on prostate cancer in both the United States and Japan.