Sujatha Nallapareddy, MD, gastrointestinal medical oncologist at Rocky Mountain Cancer Centers, discusses the use of circulating tumor DNA (ctDNA) testing in patients with colorectal cancer (CRC).

An interesting topic of discussion is that of ctDNA testing, says Nallapareddy—specifically, how this testing is utilized in CRC and when the right time to use it is. For example, if patients are getting chemotherapy, would their ctDNA be altered, and as such, would their treatment be altered? In this way, ctDNA may be considered prognostic but not yet predictive.

There remain many unanswered questions, adds Nallapareddy. Currently, ctDNA is being studied in clinical trials, and, as such, is not being used in routine practice. Therefore, Nallapareddy tends to limit its use to patients in whom there are not enough tumor samples available to test for additional targets.

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Dr. Nallapareddy on the Use of ctDNA Testing in Colorectal Cancer

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 

 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 

 wild-type. The opposite is true for patients with left-sided tumors, who should be treated with FOLFOX and cetuximab.

Sujatha Nallapareddy, MD, gastrointestinal medical oncologist, Rocky Mountain Cancer Centers, discusses treatment options for left- and right-sided colorectal cancer.

Sujatha Nallapareddy, MD

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Dr. Nallapareddy on the Use of ctDNA Testing in Colorectal Cancer

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