Table 1.

Placebo-controlled trials of aspirin for the prevention of cardiovascular disease (CVD) ± cancer reporting colorectal cancer (CRC) incidence and CRC-related mortality.

Trial (Reference)	Study Population	Number of Subjects Randomly Assigned	Treatment Groups	Median Treatment Duration (Years)	Primary End Point	RR (95% CI)
						CRC Incidence	CRC-Related Mortality
PHS [19]	Male physicians (age 40–84 years) without history of MI, stroke, cancer, liver or renal disease, gout, peptic ulcer or contraindications to aspirin	22,071	Placebo versus 325 mg aspirin alternate day	5.0	CVD and cancer	1.03 (0.83–1.28)	Not reported
WHS [21]	Women (age ≥ 45 years) without history of cancer (except non-melanoma skin cancer), CVD or other major chronic illness	39,876	Placebo versus 100 mg aspirin alternate day	10.1	CVD and cancer	0.80 (0.67–0.97)	0.80 (0.67–0.97)
BDA [22]	Male physicians without peptic ulcer, stroke or definite MI	5139	Placebo versus 500 mg aspirin per day	6.0	CVD	0.70 (0.51–0.97)	0.73 (0.49–1.10)
UK-TIA Aspirin Trial [23]	Patients with prior TIA or stroke	2449	Placebo versus 300 or 1200 mg aspirin per day	4.4	CVD	0.75 (0.56–0.97), [25] pooled with TPT and SALT	0.61 (0.43–0.87), [25] pooled with TPT and SALT
TPT [41]	High risk for IHD	5085	Placebo versus 75 mg aspirin per day (alone or with warfarin)	6.9	CVD	0.75 (0.56–0.97), [25] pooled with UK-TIA and SALT	0.61 (0.43–0.87), [25] pooled with UK-TIA and SALT
SALT [42]	Prior TIA or stroke or retinal occlusion	1363	Placebo versus 75 mg aspirin per day	2.7	CVD	0.75 (0.56–0.97), [25] pooled with TPT and UK-TIA	0.61 (0.43–0.87), [25] pooled with TPT and UK-TIA

BDA, British Doctors Aspirin Trial; CI, confidence interval; CRC, colorectal cancer; CVD, cardiovascular disease; IHD, Ischemic heart disease; PHS, Physicians’ Health Study; RR, relative risk; SALT, Swedish Aspirin Low Dose Trial; TIA, Transient Ischaemic Attack; TPT, Thrombosis Prevention Trial; UK-TIA, UK-Transient Ischaemic Attack; WHS, Women’s Health Study.