A Michigan oncologist recently devised a simple experiment to help treat seven patients with advanced, incurable cancer. The experiment used DNA microarray technology to analyze each patient’s tumors for the expression of genes associated with positive response to anti-cancer drugs. The oncologist, Dr. Eric Lester, M.D., then based his drug treatment plans on the results. Four of seven patients are reported to have had a better outcome than expected [1].

Although every cell in the body contains identical genetic material, the same genes are not active in every cell. Tumor cells are no exception. Cancer refers to any one of a large number of diseases characterized by abnormal cell growth and proliferation. Few of these diseases can be treated in the same way, since the genes responsible for a variety of biological processes — DNA duplication, cellular proliferation, cell death — are different from one tumor to the next.