Researchers studying the genetic makeup of cancerous tumors in a study published in the Sept. 7 online edition of the journal Science identified 189 genes linked to breast cancer or colorectal cancer, the Baltimore Sun reports (Bor, Baltimore Sun, 9/8). For the study, Tobias Sjoblom of Johns Hopkins University and colleagues compared the DNA codes for 13,023 genes -- about two-thirds of the total number of genes in a cell -- in cells taken from 11 cancerous breast tumors and 11 cancerous colon tumors removed from patients during surgery to DNA codes for noncancerous cells, the Wall Street Journal reports (Regalado, Wall Street Journal, 9/8). According to the study, cancerous tumors contain an average of about 90 "mutant" genes, but only some of those genes contribute to tumor growth. Researchers...