Nathan Bahary, MD, PhD, discusses treatment strategies for right- versus left-sided tumors in colorectal cancer.
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 instabilty, says Bahary. Typically, this is due to methylation of MLH1, which is sensitive to immunotherapy.
Prior to immunotherapy, patients with CRC often received EGFR inhibitors, 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.