UPDATE - Issue 12 - September 2002
Aggressive or slow growing cancer test
A simple test can now be used to identify patients with the most aggressive prostate cancers, even among patients whose tumours are at the same stage, according to research at the University of Minnesota.
The degree to which prostate cancers have progressed is currently quantified using the Gleason grading system, which is based on the shape and microscopic appearance of tumours. Patients with higher grades of tumour are in more advanced stages of the disease. Sadly, the grade does not tell how aggressively the tumours have been growing or spreading. The new test was developed by cancer researcher Akhouri Sinha, a professor of genetics, cell biology and development, at the University of Minnesota Cancer Centre. The work is published in the June 15 issue of Cancer. Donald Gleason who developed the Gleason grading system, is a co-author.
How does the test work?
In order to invade surrounding tissue and escape to blood vessels, cancer cells produce high levels of an enzyme called cathepsin B (CB), which destroys proteins in the connective tissue that holds cells in place. But cells also produce natural inhibitors of CB called stefins. The researchers reasoned that prostate tumours in which levels of inhibitors were equal to or higher than CB would be less aggressive. Conversely, if CB was higher, the tumour would be more likely to spread.
Working with prostate surgery samples from over a hundred patients, the researchers confirmed their hypothesis. "If this test were done on tumours of newly diagnosed patients" said Sinha "we would have an indication of which cancers were most aggressive, requiring aggressive treatment. Those patients whose tumours show CB to stefin A ratios of one, or less, may require less aggressive treatment. This approach could also be used for breast and colon cancer." This is precisely the sort of work the Prostate Research Campaign UK needs to support.