"If we wish to learn more about cancer, we must now concentrate on the cellular genome." Nobel laureate Renato Dulbecco penned those words more than 20 years ago in one of the earliest public calls for what would become the Human Genome Project. "We are at a turning point," Dulbecco, a pioneering cancer researcher, declared in 1986 in the journal Science. Discoveries in preceding years had made clear that much of the deranged behavior of cancer cells stemmed from damage to their genes and alterations in their functioning. "We have two options," he wrote. "Either try to discover the genes important in malignancy by a piecemeal approach, or & sequence the whole genome."

Dulbecco and others in the scientific community grasped that sequencing the human genome, though a monumental achievement itself, would mark just the first step of the quest to fully understand the biology of cancer. With the complete sequence of nucleotide bases in normal human DNA in hand, scientists would then need to classify the wide array of human genes according to their function--which in turn could reveal their roles in cancer. Over the span of two decades Dulbecco's vision has moved from pipe dream to reality. Less than three years after the Human Genome Project's completion, the National Institutes of Health has officially launched the pilot stage of an effort to create a comprehensive catalogue of the genomic changes involved in cancer: The Cancer Genome Atlas (TCGA).