Dr. Cercek on Chemotherapy Resistance in dMMR Rectal Cancer

Andrea Cercek, MD, medical oncologist, Memorial Sloan Kettering Cancer Center, discusses chemotherapy resistance in mismatch repair deficient (dMMR) rectal cancer.

Locally advanced rectal cancer is typically treated with a tri-modality therapy; this approach includes chemoradiation, surgery, and chemotherapy. It was recently discovered that moving 5-fluorouracil and oxaliplatin-based chemotherapy upfront, and following with chemoradiation and surgery can improve patient compliance with chemotherapy. This compliance, Cercek says, theoretically improves the treatment of micrometastatic disease as well as rates of complete response. This approach has now been incorporated into the guidelines as the standard of care for patients with locally advanced rectal cancer in the United States.

However, it was discovered that patients with dMMR or microsatellite instability-high rectal cancer did not respond well to chemotherapy upfront, he adds. Given this anecdotal evidence, investigators initiated a study to evaluate the sensitivity of dMMR rectal cancer to chemotherapy. In the study, the baseline characteristics, treatment modalities, and clinical outcomes of patients with dMMR rectal cancer were retrospectively reviewed.