High PSA levels may show body is fighting cancer

New research shows that prostate specific antigen (PSA), a commonly used serum marker of prostate cancer, inhibits the formation of new blood vessels and consequently slows the progression of the disease (Journal of the National Cancer Institute 1999;91:1635-40).

The finding may explain the characteristic indolent nature of most prostate cancers and calls into question experimental vaccine strategies that involve vaccinating people against the antigen.

Angiogenesis, or the formation of new blood vessels, is essential for tumour growth and metastasis, and many cancers are thought to produce angiogenic substances to promote their own growth. Accordingly, several research groups and biotechnology firms are hunting for angiogenesis inhibitors to use as antineoplastic agents.

Although used as both a screening test for …