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October 2001. Review Article.
Currently the most effective treatment of gastric cancer is surgical resection of the tumour with lymphadenectomy, which is the standard treatment in Japan.
Although gastric cancer cells, in general, have a low sensitivity to chemotherapy and a low immunogenicity related to stimulation of immune competent cells, a new method including biochemical modulation and non specific immunopotentiation with biological response modifiers (BRMs) has permitted us to augment the clinical efficacy of immunochemotherapy for gastric cancer.
Locoregional immunotherapy of gastric cancer was conducted in patients with malignant effusion using BRMs including picibanil (OK-432) and interleukin ( IL )-2. OK-432 is a liophilized, heat-inactived, penicillin treated powder of a low virulence strain of Streptococcus pyogenes A3. OK 432 strongly stimulates the cellular immune response, especially natural killer cells and macrophages, and induces the production of interleukins, interferons, and tumour necrosis factor ( TNF ). IL-2 has been well-characterized as a potent growth and differentiation factor for T lymphocytes.
Adjuvant immunochemotherapy has used BRMs including polysaccharide- K ( PSK ) and OK-432. PSK is a protein-bound polysaccharide extracted from mycelia of Coriolus versicolor ( strain CM-101 ) of Basidiomycetes, administerd orally. It has the immunopotentiating properties of 1) the restoring cancer-related immunosoppression by competing with soluble immunosuppressive factors and 2) cytokine induction of IL-1, and IL-8, as well as TNF and macrophage chemotactic factor.
Further promising new drugs are being developed and await testing for their possible benefit in an adjuvant setting, and recent advances in molecular biology may open a new avenue for tumor antigen-specific immunotherapy for gastric cancer ( 1 ).
1) T Toge. Effectiveness of immunochemotherapy for gastric cancer: a review of the current status. Seminars in Surgical Oncology, 1999; 17: 139-143.