Cryosurgery (in situ freezing) is a recognized method for the controlled cryogenic destruction of benign and malignant tissues and has been efficaciously employed for the treatment of prostatic cancer. In situ freezing constitutes an antigenic stimulus capable of generating a specific immunologic response against autologous antigens of the tissue frozen, ergo, cryostimulation. The phenomenon of cryostimulation has, in light of reports of metastatic tumor destruction, suggested that cryosurgery may be applicable not only for ablation of a primary tumor, but also as a means of inducing or augmenting host resistance to the tumor, ergo, cryoimmunotherapy. For cryosurgery to be effectual as a means of immunotherapy several factors, categorically referred to as cryosensitivity, must be fulfilled. Cryosensitivity is presently suggested to be reflective of the (i) immunogenicity of the prostate and (ii) immunocompetence of the host. The majority of prostatic cancer patients possess varying degrees of immunocompetence. Immunotherapy under such conditions may, rather than augmenting or inducing host resistance to a tumor, act in an antagonistic manner resulting in enhancement of the tumor. This knowledge has directed initial efforts of this study group toward establishment of critical criteria to evaluate the immunocompetency of the prospective cryosurgical patient. Once the degree of immunocompetency has been established, this may serve as a means to stage this patient immunologically, i.e., immunostage. Similar to traditional staging of the anatomic spread and histological grade of tumor to aid in selecting therapy and predicting outcome, immunostaging may provide adjunctive criteria toward determining a patient's suitability for cryoimmunotherapy. Directed toward improving criteria on which to immunostage patients, our initial recommendations for assessment of tumor-host immunologic responsiveness have been redefined. The principal objective being elimination, for the most part, of nonspecific correlates and maintenance and addition of specific correlates of humoral- and cell-mediated tumor-directed immunity. Preliminary studies suggest a possible relationship between a patient's immunostage and the intensity of immunologic responsiveness following cryosurgery. But, more important, the direction of the immune response, i.e., tumoricidal vs tumor enhancing. Together with observations of the association of humoral immunity with enhancement of tumor metastases and cellular immunity with regression of tumor, reports of the adjunctive utilization of modulators of the immunologic effects of cryostimulation hold promise for the more effective clinical utilization of cryoimmunotherapy.
ASJC Scopus subject areas
- General Biochemistry, Genetics and Molecular Biology
- General Agricultural and Biological Sciences