Doctors usually classify cancer by where its point of origin in the body is. Lung cancer, breast cancer, brain cancer. However, a new research study published on August 7 in the journal Cell shows that there may be a more accurate way to diagnose cancer: the genetics of the disease itself.
The research study was done at the University of California, San Francisco. One in ten cancers could be diagnosed more accurately based on genetic makeup, they suggested. The researchers also said that if we changed the diagnosis of cancer to be based on genetics, it could revolutionize treatment in the future.
"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 author Dr. Christopher Benz, a professor at the Buck Institute for Research on Aging.
The team studied 3,500 samples of tumor tissue and analyzed them for genetic makeup and molecular characteristics. They compared the tumors by RNA, DNA and proteins. Doing this, they were able to identify 12 subtypes of cancer. Of these, only five correlated with their tissue-of-origin classifications. The other seven were previously unidentified subtypes of cancer that were found to affect more than one type of tissue.
For example, the study found at least three different subtypes of bladder cancer. The researchers said that this could be why patients with bladder cancer respond differently to being treated with the same "systemic therapy for their seemingly identical cancer type."
This study was a collaboration of the Cancer Genome Atlas (TCGA) project, the National Cancer Institute and National Human Genome Research Institute. The study was done based on data that the TCGA collected since its formation in 2006. The TCGA group noticed genetic similarities in different cancer types, which led to their current "Pan-Cancer" movement.
"As we looked at more and more tumor types, it became clear that there were some subsets of tumors that reminded us of a subset we analyzed last year," said Josh Stuart, a biomolecular engineer at UC Santa Cruz who oversaw the study. "It was obvious that we should start comparing across tumor types."
As the Pan-Cancer project collects more tumor samples from different types of cancers, Benz says that he thinks many more cancer types will be reclassified; possibly as much as 30 to 50 percent.
This discovery could be a breakthrough in research for new cancer treatments.
"It will ultimately provide the biologic foundation for that era of personalized cancer treatment that patients and clinicians eagerly await," Benz says.
