Dr. Loaiza-Bonilla on Differences in Mutation Rates Between Right- and Left-Sided CRC

Arturo Loaiza-Bonilla, MD, medical oncologist, the University of Pennsylvania, discusses a study investigating differences in mutation rates between right- and left-sided colorectal cancer (CRC).

The most recent data presented regarding sidedness of CRC has been the subject of much investigation, Loaiza-Bonilla explains. It is now known that patients with right-sided tumors have worse outcomes than patients with left-sided tumors, regardless of what type of chemotherapy they receive. This knowledge spurred researchers to question if anything besides sidedness contributes to this outcome.

To address this question, researchers at the University of Pennsylvania looked at more than 250 samples of targetable genes in patients with colorectal cancer and stratified the samples between right-sided tumors and left-sided tumors. They looked for specific mutations or genomic alterations that could explain why patients with right-sided tumors have worse outcomes.

Amongst the different genomic alterations, researchers found that BRAF and CTNNB1 mutations were the most common and statistically significant among the samples. Loaiza-Bonilla notes that BRAF mutations tend to have a worse prognosis than BRAF wild type tumors. This discovery is hypothesis generating, as it may explain, to some degree, why CRC patients with right-sided tumors may have different outcomes when treated with chemotherapy.