Scientists have successfully mapped the DNA of two types of cancer, promising future treatments that will target the deadly disease.
Research teams, headed up by the Wellcome Trust Sanger Institute, said that it's the first comprehensive analysis of cancer genomes.
Cancers occur from mutations built up over the lifetime of a human being, and the scientists have mapped both a malignant melanoma and a lung cancer. The scientists said that a smoker is likely to acquire one mutation for every 15 cigarettes she or he smokes.
Malignant melanoma is a particularly pernicious form of skin cancer and three out of four skin cancer deaths are caused by it. The melanome genome showed 30,000 mutations that are records of how and when they were acquired during a patient's lifetime.
Professor Mike Stratton, at the Cancer Genome Project at the the Wellcome Trust Sanger Institute explained that these two types of cancer are the most prevalent forms for which scientists know the primary exposure.
He said: "For lung cancer, it is cigarette smoke and for malignant melanoma it is exposure to sunlight. With these genome sequences we have been able to explore deep into the past of each tumor, uncovering with remarkable clarity the imprints of these environmental mutagens on DNA, which occurred years before the tumor became apparent."
The human genome, he continued, desperately attempts to defend itself against the damage caused by the chemicals in cigarette smoke and ultraviolet radiation. "Our cells fight back furiously to repair the damage, but frequently lose that fight."
The lung cancer genome had over 23,000 mutations and the melanoma 33,000. Dr Peter Campbell from the Wellcome Trust Sanger Institute said: "The knowedge we extract over the next few years will have major implications for treatment. By identifying all the cancer genes, we will be able to develop new drugs that target the specific mutated genes and work out which patients will benefit from these novel treatments," he said.