Dr. Bahary on Treatment Strategies for Right- Versus Left-Sided Tumors in CRC

Nathan Bahary, MD, PhD, associate professor, University of Pittsburgh School of Medicine, medical oncologist and hematologist, University of Pittsburgh Medical Center​ Hillman Cancer Center, discusses treatment strategies for right- versus left-sided tumors in colorectal cancer (CRC).

Patients with right-sided tumors ​tend to have more microsatellite instab​ilty, says Bahary. Typically, ​this is due to methylation of MLH1, which is sensitive to immunotherapy.

Prior to immunotherapy, patients with CRC ​often received EGFR inhibitor​s, such as cetuximab ​(Erbitux) or panitumumab ​(Vectibix), says Bahary. However, past research ​revealed that patients with KRAS, BRAF, orNRAS mutations do not derive benefit from EGFR inhibitors alone. 

Furthermore, in the metastatic setting, ​patients with right-sided tumors do not respond to the combination of chemotherapy and EGFR inhibitors, whereas ​patients with left-sided tumors can respond to such combinations, Bahary explains.

As such, patients with ​metastatic CRC and right-sided tumors ​should receive bevacizumab (Avastin) or anequivalent anti-VEGF agent, Bahary concludes.