The role of neoadjuvant treatment in colon cancer continues to evolve, particularly as researchers explore whether immunotherapy could offer benefits beyond the currently established treatment approach.
During a question-and-answer session, Stefanie Perna-Nacar invited Myriam Chalabi, MD, to discuss how frequently patients with microsatellite-stable, or MSS, disease currently receive treatment before surgery and whether neoadjuvant immunotherapy could eventually become part of routine clinical practice.
How Often Is Neoadjuvant Treatment Used in MSS Disease?
Dr. Chalabi explained that the use of neoadjuvant treatment has gradually increased following the Foxtrot study. However, for patients with MSS disease, the treatment given before surgery is currently chemotherapy rather than immunotherapy.
Neoadjuvant chemotherapy may be considered when clinicians believe the tumor needs to become smaller to allow the surgeon to remove it completely and more easily.
It may also be used when the tumor characteristics observed at diagnosis suggest that the patient will probably require chemotherapy after surgery. In these situations, the treatment can instead be delivered before surgery, with the additional potential benefit of reducing the tumor size.
Despite this changing approach, Professor Chalabi emphasized that only a small proportion of patients with MSS colon cancer currently receive neoadjuvant treatment.
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Moving Treatment From After Surgery to Before Surgery
The standard treatment pathway for many patients continues to involve surgery followed by a decision regarding adjuvant chemotherapy. However, Dr. Chalabi noted that this sequence may change when a neoadjuvant treatment demonstrates better outcomes than the available postoperative option.
“When you have a treatment that is superior to what we’re doing in the adjuvant setting, that will shift to the neo,” she said.
This transition has already started to become visible in patients with microsatellite instability-high, or MSI-high, tumors.
Lessons From MSI-High Colon Cancer
Neoadjuvant immunotherapy has produced exceptional responses in MSI-high tumors, encouraging clinicians to increasingly consider treatment before surgery.
Dr. Chalabi acknowledged that neoadjuvant immunotherapy has not yet become standard of care everywhere for MSI-high colon cancer. Nevertheless, clinical practice has already begun shifting toward greater use of immunotherapy in the neoadjuvant setting because of the responses observed and the potential advantages over previous treatment options.
The experience in MSI-high disease provides an important example of how strong clinical evidence can alter the timing and selection of treatment.
What Could Make Neoadjuvant Immunotherapy Practice-Changing?
The central question for MSS disease is whether neoadjuvant immunotherapy can demonstrate superiority over the current standard approach, particularly adjuvant chemotherapy.
According to Dr. Chalabi, if clinical trials show that immunotherapy delivered before surgery is more effective than standard postoperative chemotherapy, the findings could make it substantially easier to treat a much broader population in the neoadjuvant setting.
The success of such an approach would therefore represent more than the introduction of another treatment option. It could reshape the overall treatment pathway for patients with MSS colon cancer, moving systemic therapy earlier and expanding the number of patients considered for treatment before surgery.
For now, neoadjuvant treatment remains limited to a relatively small proportion of patients with MSS disease. However, evidence demonstrating that neoadjuvant immunotherapy is superior to the current adjuvant standard could lead to a major change in clinical practice.
Written by Nare Hovhannisyan, MD