Michael White explains why a cure for cancer has been so elusive:
Cancer genome projects are the latest front in the War on Cancer. The U.S. National Institutes of Health created The Cancer Genome Atlas (whose acronym, TCGA, consists of the abbreviations for each of the four chemical letters in DNA), and the United Kingdom’s Wellcome Trust is assembling the Catalog of Somatic Mutations in Cancer (COSMIC). The goal of projects like these is to exhaustively map out the genetic terrain of cancer by identifying every mutation in the genomes of tumors from tens of thousands of cancer patients. The hope motivating these projects was that scientists would discover a core set of cancer driver mutations for each type of cancer, mutations that could be targeted with smart drugs.
What researchers have discovered instead is that cancer is a much more fiendishly complicated genetic mess than we ever imagined. Instead of a handful of cancer-causing driver mutations for each cancer type, scientists have found that there are many different genetic paths to the same cancer. Many driver mutations for a particular cancer type occur in less than 20 percent of cancers of that type, which means that drugs targeted at that mutation will only help a minority of patients. A recent review of the subject noted that the COSMIC project has cataloged more than 800,000 mutations, covering nearly every gene in the human genome. The authors of the review suggested that “the cast of genes involved in any single cancer type will be in the neighborhood of 50–100.”
The Dish 