Dr. Kopetz on the Significance of Tumor Sidedness in CRC

Scott Kopetz, MD, PhD, FACP, associate professor, Department of Gastrointestinal Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, discusses the significance of tumor sidedness in colorectal cancer (CRC).

Researchers have known for many years that there are biological differences between left- and right-sided CRC, the clinical implications of which have become apparent over the last few years. Right-sided CRC is associated with a particularly poor prognosis and a lower progression-free survival (PFS) on standard therapy. Tumor origin also plays a role in recurrence after liver metastasis resection, Kopetz says.

Moreover, many studies have indicated there is a difference in response to targeted therapy in right- versus left-sided CRC. This is particularly true for EGFR inhibitors, cetuximab (Erbitux) and panitumumab (Vectibix). Tumors on the right side of the colon, even if they are wild-type tumors, still have a poor response to EGFR inhibition. This is also associated with lower PFS, says Kopetz.