Patients with stage III colon cancer who used aspirin and COX-2 inhibitors demonstrated statistically significant reductions in risk for cancer recurrence and mortality, according to results of a prospective observational study.
The analysis — conducted by Kimmie Ng, MD, medical oncologist at Dana-Farber Cancer Institute, and colleagues — included patients enrolled in the CALGB 89803 trial, which compared fluorouracil and leucovorin with or without irinotecan as adjuvant chemotherapy for patients with stage III colon cancer.
Participants completed self-administered questionnaires midway through chemotherapy and 6 months after chemotherapy to assess diet, lifestyle and medication use.
According to researchers, 799 patients responded to questions about aspirin use. Results showed aspirin use was associated with improved RFS (HR=0.51; 95% CI, 0.28-0.95), DFS (HR=0.68; 95% CI, 0.42-1.11) and OS (HR=0.63; 95% CI, 0.35-1.12).
Adjusted HRs, censored at 5 years to minimize misclassification from noncancer death, were 0.61 (95% CI, 0.36-1.04) for DFS and 0.48 (95% CI, 0.23-0.99) for OS.
Patients who used five or more tablets per week had an HR of .69 (95% CI, 0.41-1.18) as compared with nonusers (P=.15).
Researchers determined 843 patients responded to questions about COX-2 inhibitor use. Results showed use was associated with improved RFS (HR=0.53; 95% CI, 0.27-1.04), DFS (HR=0.6; 95% CI, 0.33-1.08) and OS (HR=0.5; 95% CI, 0.23-1.07). Adjusted HRs, censored at 5 years, were 0.47 (95% CI, 0.24-0.91) for DFS and 0.26 (95% CI, 0.08-0.81) for OS.
Patients who used one to four tablets per week had HR of 0.59 (95% CI, 0.22-1.59) and those who used five or more tablets per week had an HR of 0.50 (95% CI, 0.21-1.23) compared with nonusers (P=.14).
“The strengths of our study include its prospective nature, as well as the fact that the patient population was drawn from a large, randomized, intergroup trial that had high-quality, comprehensive data on patient and tumor characteristics and recurrence and survival,” Ng told HemOnc Today. “The next step is to confirm our findings with randomized clinical trials of aspirin use in resected stage III colon cancer patients.”
Two such trials, CALGB/Alliance 80702 and the ASCOLT study, are underway.
“There are also many other unanswered questions,” Ng said. “[They include] the exact mechanism of action underlying the benefit seen with aspirin and COX-2 in colon cancer, what the optimal duration and dose of these medications are, and what subgroups of colon cancer patients benefit most from use of these medications.”
Disclosure: The study was supported by the NCI, the NIH, and the Conquer Cancer Foundation of the American Cancer Society.