Dr. Fuchs on Aspirin for the Treatment of Colorectal Cancer
Charles S. Fuchs, MD, MPH, director, Gastrointestinal Cancer Center, Dana-Farber Cancer Institute, discusses the use of aspirin for the prevention and treatment of colorectal cancer.
Studies have suggested that aspirin can reduce the risk of colorectal polyps or cancer, Fuchs says, providing level 1 evidence for aspirin as a preventative agent. More recently, researchers have looked to see if aspirin can provide benefit for patients with established colorectal cancer.
Several trials have collected information on aspirin use in patients who have started chemotherapy for stage 1, 2, or 3 colorectal cancer. In all of these observational studies, those patients who reported aspirin use had significant improvement in cancer-free survival. The next step, Fuchs says, is to define biomarkers and understand the mechanisms of aspirin.
It is widely believed that one target for aspirin is cyclooxygenase-2 (COX-2), a marker that affects an increased proliferation in cancer cells. As approximately two-thirds of colon cancers overexpress COX-2, the question presented itself as to whether or not aspirin would be more effective in a tumor that overexpressed COX-2.
In the laboratory, Fuchs says, it was seen that in those two-thirds of patients whose tumors overexpressed COX-2, they saw significant improvement in survival. Conversely, if a tumor did not overexpress COX-2, the benefit of aspirin was minimal.
As all of the studies looking at aspirin in colorectal cancer have been observational, Fuchs says there is a need for randomized trials like CALGB 80702. In this trial, patients who have been resected for stage 3 colon cancer will receive chemotherapy and will be randomized to a COX-2 inhibitor (not aspirin). This trial aims to answer the question as to whether COX-2 inhibition can contribute to survival benefit in this space.