US scientists have cracked the entire genetic code of breast and colon cancers, offering new treatment hopes.
Faulty genes help cancers grow
The genetic map shows that nearly 200 mutated genes, most previously unknown, help tumours emerge, grow and spread.
The discovery could also lead to better ways to diagnose cancer in its early, most treatable stages, and personalised treatments, Science magazine reports.
The Johns Hopkins Kimmel Cancer Center says the findings suggest cancer is more complex than experts had believed.
The mutated genes in breast and colon cancers were almost completely distinct, suggesting very different pathways for the development of each of these cancer types.
Each individual tumour appeared to have a different genetic blueprint, which could explain why cancers can behave very differently from person to person, the scientists said.
"No two patients are identical," co-author Dr Victor Velculescu explained.
Now researchers will study how these mutations occur in breast and colon cancers.
Previous cancer gene discoveries have already led to successful detection and treatment strategies.
For example, the breast cancer drug Herceptin targets a breast cancer cell receptor made by the Her2-neu gene. Blood tests for hereditary bowel cancer are based on the APC gene.
Dr Anna Barker, of the National Cancer Institute, said: "Maximising the numbers of targets available for drug development in a specific cancer means that patients will ultimately receive more personalised, less toxic therapies."
Ed Yong, of Cancer Research UK, commented: "This is potentially a very important piece of research.
"Most of the cancer genes identified in this study have not been previously linked to cancer.
"These newly identified genes could provide rich hunting grounds for scientists looking for new ways of treating or detecting cancers.
"In the future, scientists hope to be able to tailor plans for preventing or treating cancer to each person's individual genetic profile. Studies like this can help us to accomplish this goal."