Researchers Identify Genes Linked to Some Cancers

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 identified 189 mutant genes that frequently were found in the cancerous tumors (Sjoblom et al., Science, 9/7). Researchers linked 122 of the genes to breast cancer and 69 to colon cancer, and only two genes were linked to both cancers.

Although some of the mutated genes might be hereditary, most develop during a person's life, according to Bert Vogelstein, co-director of the Ludwig Center at Johns Hopkins and co-author of the study. "From the first mutation to a full-blown malignancy, it takes literally 20 to 40 years," Vogelstein said, adding, "This data could explain why it takes so long." He also said that a person would have to have around 20 of the genetic mutations to develop cancer (Baltimore Sun, 9/8).

The study -- which cost $5 million -- was funded by private donations, Kenneth Kinzler, a cancer researcher at Johns Hopkins and co-author of the study, said (Wall Street Journal, 9/8).

NIH Director Elias Zerhouni said the study "f[o]r the first time ... tells us that you could identify what in cancer is the Achilles' heel," adding, "Instead of doing what we do now, which is to give the standard treatment for everybody, we will adjust the treatment for each patient and hopefully dramatically affect their cancer."

Physicians previously knew about 10 genes linked to breast or colorectal cancers, USA Today reports (Szabo, USA Today, 9/8).

"The large number of mutations reported in [the Science study] offers a glimpse of what is yet to come and provides exciting new directions for drug discovery in breast and colon cancer," Francis Collins, head of genetics at NIH, said (AP/Forbes, 9/7).