Immunostimulation by cryosurgery: an orthotopic model of prostate and bladder cancer in the rat.

In patients with prostate cancer, cryosurgery has been highly effective in eradication of the primary tumor. Certain clinical observations have suggested the presence of an additional systemic anticancer effect, presumably immunologic in nature, but proof is lacking. To study this problem further, we developed two animal tumor models. Instead of using the classical subcutaneous site, we transplanted the 11095A and R-3327 prostate tumors into rat prostate, the 4909 bladder tumor into rat bladder. In these respective orthotopic locations, the 3 tumors displayed favorable growth characteristics with good accessibility for cryosurgery. This model should be considered for studies involving any localized treatment of an established urologic tumor.