In the battle against cancer, knowing a tumor's genomic profile may be more important to treating it than where it has occurred in the human body or how much it has grown, researchers say.
In a study analyzing more than 3,000 tumor specimens of a dozen different types of cancer, the researchers concluded 10 percent of cancer patients could be offered improved therapies if their doctors had better information on their particular tumor's DNA and its exact expression.
Genetics analysis can provide doctors with "clinically relevant prognostic information above and beyond tumor stage and primary tissue-of-origin," the researchers wrote in a report on their study in the journal Cell.
Up to now, cancers have been characterized by their location of their origin in the body, so cancer cells growing in the lung are "lung cancer" while those originating in the stomach or pancreas are "stomach cancer" or "pancreatic cancer."
Now, researchers suggest cancer should be thought about in terms of genetic and molecular characteristics rather than just a broad "location" classification.
Identifying the kind of cell causing the cancer, instead of fixating on the tissues in the body where it started, could possibly lead to better future treatments, the suggest.
In their study of tumor specimens, utilizing a mathematical technique to group tumors based on genomic similarities, they found that of the dozen cancer types they looked at, only five matched with traditional categorizations based on tissue or organ of origin.
The rest, they said, were previously unidentified varieties capable of affecting more than a single kind of tissue, which would not match the old "origin" system of classification.
They showed a high degree of difference despite being considered the same cancers based on just location within the body, they said.
"They looked like different tissues," said study leader Josh Stuart, a biomolecular researcher at the University of California, Santa Cruz.
As an example, the study identified three separate, different varieties of bladder cancer, which could explain why individual patients often have different responses to therapy for one apparently identical type of cancer.
Further studies of more tumor specimens and cancer types will likely lead to many cancers being reclassified and better identified in terms of most appropriate treatment, the researchers suggest.
"This genomic study not only challenges our existing system of classifying cancers based on tissue type but also provides a massive new data resource for further exploration," says co-senior study author Dr. Christopher Benz.
"It will ultimately provide the biologic foundation for that era of personalized cancer treatment that patients and clinicians eagerly await," he says.
