Dr. Nallapareddy on Treatment Options for Left- and Right-Sided CRC

Sujatha Nallapareddy, MD, medical oncologist, Rocky Mountain Cancer Centers, discusses treatment options in left- and right-sided colorectal cancer (CRC).

Until recently, researchers were not very clear on the differences between left- and right-sided CRC, Nallapareddy says. The CALGB/SWOG 8045 trial showed that right-sided tumors behave differently from those on the left side of the colon. With these data, physicians now know that patients with left-sided tumors have a better prognosis than those with right-sided tumors. However, researchers don’t yet know if this has to do with the microbiome or KRAS and BRAF alterations that are often present in right-sided CRC.

EGFR antibodies appear to work better in left-sided tumors, whereas VEGF antibodies work better in right-sided tumors. As such, a patient with metastatic right-sided CRC should receive FOLFOX with bevacizumab (Avastin) instead of FOLFOX with cetuximab (Erbitux), even if they are KRAS wild-type. The opposite is true for patients with left-sided tumors, who should be treated with FOLFOX and cetuximab.