Scientists have identified 189 mutated genes that may cause breast and colorectal cancers, according to a study published Thursday in Science.

The findings could lead to new treatments for cancer, better ways to diagnose it, and certainly will provide insights into the second-leading cause of death in the developed world, the researchers said.

The researchers examined more than 13,000 genes in 11 different breast tumors and 11 colorectal cancers, removed from patients during surgery.

The work stresses that cancers differ greatly from organ to organ: Mutations in the breast tumors are substantially different from those in the colorectal tumors.

Researchers also were surprised to find that each tumor they analyzed was different. Even tumors of the same organs had only about five genes in common, which could shed light on why many chemotherapy drugs help only a fraction of patients.

"For the first time, this tells us that you could identify what in cancer is the Achilles heel," said Elias Zerhouni, director of the U.S. National Institutes of Health, which partially financed the research, "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."

Researchers focused on breast and colorectal cancers because they are two of the leading cancer killers. More than 210,000 cases of breast cancer are diagnosed each year in U.S., and 40,000 people die of the disease; 145,000 cases of colorectal cancer are diagnosed each year, and 56,000 people die.

Source: Xinhua/agencies