Dr. Cercek on Induction Chemotherapy in Mismatch Repair Deficient Rectal Cancer

Andrea Cercek, MD, medical oncologist, Memorial Sloan Kettering Cancer Center, discusses induction chemotherapy in patients with mismatch repair (MMR) deficient rectal cancer.

The responsiveness to chemotherapy remains uncertain in the population of patients with rectal cancer who are MMR deficient. There are data that have shown that patients who have MMR deficient colorectal adenocarcinoma do not respond to chemotherapy in the metastatic setting.

In a study of patients with Lynch syndrome and MMR deficient rectal cancer, 26% of those who received neoadjuvant chemotherapy with either FOLFOX or capecitabine and oxaliplatin had disease progression. The majority of these patients harbored germline mutations in the MMR genes. This is concerning for rectal cancer, Cercek says, because induction chemotherapy usually is successful in patients.

Cercek says that these data highlight the need for immunohistochemistry to be checked in patients with locally advanced rectal cancer, because a small portion of them have MMR deficiency. Additionally, if a patient has known Lynch syndrome or is microsatellite instability-high, they should not receive neoadjuvant chemotherapy.