Table 1.

Basic characteristics of studies.

Author	Year of publication	Origin	Type of study	Follow-up time	Number of samples (n)	Use aspirin/no use (n)	Outcome	Breast cancer-specific death	All-cause death	Recurrence/metastasis
Blair CK[16]	2007	America	Cohort study	1992–2001	591	254/337	1,2	0.53 (0.30,0.93)	0.53 (0.36,0.79)
Wernli KJ[17]	2011	America	Cohort study	1998–2006	3022	1059/1963	1,2	0.64 (0.37,1.37)	0.91 (0.65,1.29)
Li Y[18]	2012	America	Cohort study	1996–2006	1024	Not clear	1,2	0.89 (0.53,.52)	0.82 (0.54,1.24)
Fraser DM[11]	2014	England	Cohort study	1998–2008	2617	815/1802	1,2	0.42 (0.31,0.55)	0.53 (0.45,0.63)
Barron TI[19]	2014	Ireland	Cohort study	2000–2006	2796	740/2056	1,2	0.99 (0.68, 1.45)	1.11 (0.83, 1.50)
Barron TI[20]	2015	Ireland	Cohort study	2001–2012	4540	764/3776	1,2	0.98 (0.74,1.30)	1.10 (0.90,1.33)
Bradley MC[21]	2016	America	Cohort study	1993–2009	2925	1274/1651	1,2	0.95 (0.68,1.31)	0.93 0.75,1.15
Shiao J[22]	2016	America	Cohort study	1998–2016	222	65/157	1,2,3	0.41 (0.20,0.83)	0.67 (0.35,1.27)	0.34 (0.15,0.81)
Mc Menamin MC[23]	2017	England	Cohort study	2009–2015	15,140	2822/12,318	1,2	0.92 (0.75,1.14)	1.21 (1.04,1.40)
Wang T[24]	2019	America	Cohort study	1996–2014	1442	301/1141	1,2	0.87 (0.59,1.29)	1.21 (0.99,1.48)
Frisk G[25]	2018	Sweden	Cohort study	2006–2012	21,414	9582/11,832	1,3	0.99 (0.79, 1.23)		0.97 (0.86,1.10).
Cronin-Fenton DP[26]	2016	Denmark	Cohort study	1996–2008	34,188	6802/27,386	3			1.0 (0.85, 1.3)
Bens A[27]	2018	Denmark	Cohort study	1996–2012	52,723	5295/47,428	3			0.88 (0.69,1.13)

Note: 1: Breast cancer-specific death; 2: all-cause death; 3: recurrence (metastasis).