Aspirin, cyclooxygenase inhibition and colorectal cancer

Table 1 Summary of the associations between regular use of aspirin and risk of colorectal cancer in case-control and cohort studies

Study type	n	Aspirin	Controls	OR (95%CI)	P value
Case-control
Any ASA	26	10464/25618	28300/47834	0.67 (0.60-0.74)	< 0.0001
Maximum reported ASA	17	1551/12659	2664/18153	0.62 (0.58-0.67)	< 0.0001
ASA ≥ 5 yr	10	971/7682	1534/10029	0.68 (0.63-0.75)	< 0.0001
Daily ASA	4	165/1254	349/1523	0.49 (0.40-0.60)	< 0.0001
Daily ASA ≥ 5 yr	1	66/1668	121/1973	0.63 (0.46-0.86)	0.004
Standard cohort
Any Aspirin	11	3791/2764414	3623/2514652	0.85 (0.82-0.89)	< 0.0001
Maximum reported ASA	8	661/664475	1858/1374905	0.78 (0.71-0.84)	< 0.0001
ASA ≥ 5 yr	4	889/1 022192	1311/1304760	0.76 (0.70–0.82)	< 0.0001
Daily ASA	5	741/658536	1115/819288	0.80 (0.73-0.88)	< 0.0001
Daily ASA ≥ 5 yr	1	60/38302	420/232116	0.68 (0.52-0.90)	0.0060
Nested case-control
Any ASA	6	2215/8926	65 099/109526	0.87 (0.75-1.00)	0.0700
Maximum reported ASA	5	206/4457	8302/40948	0.67 (0.58-0.77)	< 0.0001
ASA ≥ 5 yr	1	116/228	23704/37935	0.62 (0.48-0.81)	< 0.0001
Daily ASA	1	53/165	8744/22975	0.77 (0.55-1.07)	0.1400
Daily ASA ≥ 5 yr	1	29/141	7274/21505	0.51 (0.34-0.76)	0.0120

Modified from Algra et al[8]. Estimates from standard cohort studies are based on results adjusted for age and other baseline clinical characteristics. ASA: Aspirin.