Researchers have discovered a single gene which may define the difference between a fast growing tumor and a slow growing tumor for Thymoma, a rare form of cancer. Thymoma is a cancer derived from the epithelial cells of the thymus, an organ critical to the lymphatic system where T-cells, or so-called "killer cells," mature.

Very little is known about the role of the gene mutation GTF2l in human tumors, but scientists from Georgetown Lombardi Comprehensive Cancer Center and the National Cancer Institute say almost all indolent (slow growing and non-aggressive) forms of thymoma they tested have the mutation. They report their finding in the issue of Nature Genetics. "Indolent thymomas seldom become aggressive, so the discovery that a single gene can identify tumors that do not need aggressive care is an important development for our patients," says the study's senior investigator, Giuseppe Giaccone, MD, PhD, associate director for clinical research at Georgetown Lombardi.

In addition to the clinical implications, the study is important because "it is highly unusual to find a single mutated gene that can define a class of tumors," he said. "Usually a substantial number of genes are involved. In fact, we also found that the more aggressive thymomas express well-known cancer genes found in other tumors — which might give us clues about novel treatment of these cancers."