Is immunoprophylaxis of cancer possible?

With the three modalities of cancer treatment, surgery, radio- and chemo-therapy, even when applied in optimal conditions, over 50% of patients remain incurable because of metastatic disease. Hence the importance of preventive methods of approach to cancer. Host human tumors arise in renewing cell populations, while others, which originate in tissues with a slower rate of proliferation, are often preceded by tissue injury, which induces an adaptive proliferation (irritants, viruses, hypoxia etc.). Prospective and retrospective studies have shown that a "precancerous lesion" (intraepithelial neoplasia), meaning a certain histopathological substratum which, when not disturbed in its natural history through diagnostic or therapeutic proceedings, can evolve in a significant proportion, to invasive cancer. Our earlier studies have revealed a specific host-resistance to placental suspension (PS) when injected intradermally in patients with clinical conditions having, as histopathological substratum, an adaptive cellular proliferation. These findings suggest that a successful immunologic approach for adaptive proliferation is a boosted cell-mediated hypersensitivity reaction which, as an adjunct to other therapies, would eliminate and thus prevent the progression of adaptive proliferation towards neoplasia. A vaccine consisting of PS used as an immunogen, mixed with and adjuvant (BCG) may allow the strengthening of what is a natural but ineffective bodily response to the problem of adaptive proliferation. It is easier to eliminate immunologically an antigenic homogeneous cellular proliferation process than a neoplastic one which is antigenically heterogeneous. The induction of cell-mediated hypersensitivity reaction by a PS + BCG vaccine in healthy people would also be a primary immunoprophylaxis for some solid tumors in man.(ABSTRACT TRUNCATED AT 250 WORDS)