Background/aims: Warfarin and aspirin are commonly used to prevent cardiovascular diseases. Aspirin was recently found to have chemopreventive effects on colon cancer and polyps by inhibiting cyclooxygenase-2. Therefore, we evaluated whether the symptoms of bleeding related with aspirin or warfarin could be a clue in early detection of colon cancer. We also assessed the effect of aspirin on the development of synchronous polyps.
Methods: A total of forty-one and 16 patients diagnosed as colon cancer, taking aspirin or warfarin respectively were enrolled. In addition, 171 patients with colon cancers were age and gender matched as a control group. We investigated the difference of clinical features and laboratory findings among three groups.
Results: The incidence of bleeding was 81.3% (warfarin), 53.7% (aspirin), 40.4% (control). Among three groups, location and size of cancer, number of lymph nodes involvement and stages were not different, but the number of patients in Duke stage D in warfarin group (n=1, 6.3%) were less than that of the control (n=44, 25.7%) (p=0.049). The extent of circumferential involvement by cancer was lower in aspirin group (67%) than in the control group (80%) (p=0.035). The percentage of patients with synchronous polyps and mean number of synchronous polyps in aspirin group (34.1%, 0.68, respectively) was lower than that of control group (53.6%, 1.69, respectively) (p=0.029, 0.008, respectively).
Conclusions: Bleeding related with aspirin or warfarin usage had no effect on the early diagnosis of colon cancer. However, lower incidence of Duke stage D in warfarin group might be related to anti-metastatic effect of warfarin. In addition, aspirin may have a role in suppressing the development of synchronous polyps.