Alberto Sobrero, MD, who discussed the VICTOR trial at the European Cancer Congress, said that at this point, adjuvant trials may be unethical, if the findings of multiple observational studies are to be trusted. Apparently, Dr. Sobrero is a believer: He introduced his remarks at the ECC session by swallowing an aspirin before the audience. “This is an aspirin. It’s the strongest message I can give. The relevance of this study, to me, is absolutely fantastic,” he said.

“Zero out of 14 patients taking aspirin relapsed, vs 23 of 90 patients not taking aspirin. That’s a hazard ratio of 0.11, which means that those not taking aspirin have more than an eight times increased risk of recurrence,” he pointed out. “If the observational data are true, then for every patient relapsing or dying on aspirin, 8 to 10 relapse or die if they are not using aspirin.”

Patients with colorectal cancer are tuning into the data from the observational studies and are not likely to agree to be randomly assigned to placebo, which would convey an eight times greater risk of recurrence, if these data are correct, he pointed out. Others might enroll but then contaminate the study by taking aspirin on the sly, he suggested.

To ensure an ethical basis and reliable results from a randomized adjuvant trial, a stringent stopping rule would need to be in place, he said. ■

Disclosure: Dr. Sobrero reported no potential conflicts of interest.