A new study sheds light on how tumors evolve

As with most cancers, triple-negative breast cancer (TNBC) cells have abnormal amounts of chromosomes or DNA copy number aberrations (CNAs) in their genomes. A new study used single-cell sequencing technology to provide previously unknown details about how and when CNAs impact tumor formation and growth.

The study’s results, published in the online issue of Nature Genetics, challenge the prevailing belief that CNAs take place slowly and gradually over time. Instead, researchers found that chromosomal changes occur in short, punctuated “bursts” at the earliest stages of tumor growth.

“The current model asserts CNAs are acquired gradually and sequentially over extended periods of time, leading to successively more malignant stages of cancer,” said Nicholas Navin, Ph.D., professor of Genetics at MD Anderson and lead author of the paper. “Another model is punctuated evolution in which CNAs are acquired in short bursts of crisis, followed by stable clonal expansion that form the tumor mass. Our study suggests punctuated copy number evolution is common in TNBC patients.”

Navin’s study supports the “bursts” model and demonstrates that the majority of CNAs are acquired at the earliest stages of tumor evolution. This discovery is important, Navin said, because most genomic studies have focused on a single point in time, after a tumor has been surgically removed, making it difficult to study the natural history of chromosome evolution during tumor growth.

The new knowledge generated from this study could impact how cancer is diagnosed and treated in the future, Navin said.

Learn more about these findings in the MD Anderson Newsroom.