Table 1.
Baseline characteristics of included studies
| Study | Country | Study design | Cancer type | Sample size | Age at CRC diagnosis, y | Stage (AJCC/Duke) | Follow-up duration, y | Outcome indicators | Dose-response | Duration-response |
|---|---|---|---|---|---|---|---|---|---|---|
| Chan AT et al. 2009 (29) | US | Cohort study (NHS/HPFS) | CRC | 1279a | NA | I-III | Median = 11.8 | CRC-specific mortality, overall mortality | 0.5-5 tablets/wk, ≥6 tablets/wk | — |
| Zell JA et al. 2009 (30) | US | Cohort study (CTS) | CRC | 621b | NA | I-IV | Median = 2.8; mean = 3.4 | CRC-specific mortality, overall mortality | — | <5 y, ≥ 5 y |
| Din FV et al. 2010 (31) | UK | Case-control study (SOCCS) | CRC | 2063a | Mean = 62.2 | NA | NA | CRC-specific mortality, all-cause mortality | — | — |
| Coghill AE et al. 2011 (14) | US | Cohort study | CRCd | 1737a | NA | I-IV | Mean = 8 | CRC-specific mortality | — | — |
| Bastiaannet E et al. 2012 (15) | Netherland | Cohort study | CRCd | 4481a | Median = 69 | I-IV | Median = 3.5 | Overall survival | — | — |
| Liao X et al. 2012 (18) | US | Cohort study (NHS/HPFS) | CRC | 964a | Mean = 68 | I-IV | Median = 12.7 | CRC-specific mortality, overall mortality | — | — |
| Reimers MS et al. 2012 (32) | Netherland | Cohort study | CRC | 536a | Median = 77.6 | I-IV | NA | Overall survival | — | — |
| Walker AJ et al. 2012 (33) | UK | Cohort study | CRC | 13 944a | User, mean = 68.3; Nonuser, mean = 74.5 | I-IV | NA | All-cause mortality | Prophylaxis dose, high dose | 0-5 y, 5-10 y, >10 y |
| Chae YK et al. 2013 (51) c | US | Cohort study | CRC | 243a | Mean = 58 | NA | NA | All-cause mortality | — | — |
| Domingo E et al. 2013 (19) | UK | Cohort study (VICTOR trial) | CRC | 896a | Median = 64.6 | II-III | Median = 5.1 | Overall survival, RFS | — | — |
| McCowan C et al. 2013 (34) | UK | Cohort study | CRCd | 2990a | Median = 73 | Duke A-D | NA | CRC-specific mortality, all-cause mortality | — | — |
| Sun R et al. 2013 (52)c | US | Cohort study (NHS/HPFS) | CRC | 931a | NA | I-IV | NA | CRC-specific mortality | — | — |
| Cardwell CR et al. 2014 (16) | UK | Nested case-control study | CRCd | 4794a | NA | I-IV | NA | CRC-specific mortality, all-cause mortality | — | <1 y, ≥1 y |
| Goh CH et al. 2014 (35) | Singapore | Cohort study | CRC | 726a | Median = 65 | I-III | NA | CRC-specific mortality, RFS | — | — |
| Reimers MS et al. 2014 (20) | Netherland | Cohort study | CC | 999a | NA | I-IV | NA | Overall survival | — | — |
| Kothari N et al. 2015 (36) | Australia | Cohort study | CRC | 185a | Median = 72 | I-IV | Median = 4.5 | Cancer-specific survival, overall survival | — | — |
| Ng K et al. 2015 (37) | US | Cohort study (CALGB89803 trial) | CC | 799a | NA | III | Median = 6.5 | Overall survival, RFS, DFS | — | — |
| Restivo A et al. 2015 (38) | Italy | Cohort study | RC | 241a | Median = 65 | II-III | Median = 3.08 | Overall survival, PFS | — | — |
| Zanders MM et al. 2015 (39) | Netherland | Cohort study | CRCd | 1043a | Mean = 73.2 | I-IV | Mean = 3.4 | All-cause mortality | — | — |
| Babic A et al. 2016 (40) | US | Cohort study (NHS/HPFS) | CRC | 544a | NA | I-IV | NA | Overall mortality | — | — |
| Bains SJ et al. 2016 (41) | Norway | Cohort study | CRCd | 23162a | Mean = 71.5 | I-IV | Median = 3 | Cancer-specific survival, overall survival | — | — |
| Frouws MA et al. 2017 (42) | Netherland | Cohort study | CRC | 6335a | NA | I-IV | NA | Overall survival | — | — |
| Frouws MA et al. 2017 (43) | Netherland | Cohort study | CRC | 7006a | NA | I-IV | NA | Overall survival | — | — |
| Frouws MA et al. 2017 (44) | Netherland | Cohort study | CRC | 599a | NA | I-IV | NA | Overall survival | — | — |
| Giampieri R et al. 2017 (45) | Italy | Cohort study | CRC | 66a | NA | NA | NA | Overall survival, PFS, disease control rate | — | — |
| Gray RT et al. 2017 (21) | Northern Ireland | Cohort study | CC | 740a | NA | II-III | Mean = 5.7 | Cancer-specific survival, overall survival | — | — |
| Hamada T et al. 2017 (22) | US | Cohort study (NHS/HPFS) | CRC | 617a | Mean = 68.6 | I-IV | Median = 11.5 | Cancer-specific survival, overall survival | — | — |
| Hua XW et al. 2017 (17) | US | Cohort study | CRC | 2419a | Mean = 54 | I-IV | Median = 10.8 | Cancer-specific survival, overall survival | — | ≤3 y, >3 y |
| Murphy C et al. 2017 (46) | Australia | Cohort study | CC | 488a | Median = 72 | II | NA | Overall survival, RFS | — | — |
| Gray RT et al. 2018 (47) | Northern Ireland | Cohort study | CRCd | 8391a | NA | Dukes A-C | Median = 3.6 | CRC-specific survival, overall survival | 1-365 daily defined dose, >365 daily defined dose | — |
| Rouette J et al. 2018 (53)c | Canada | Cohort study | CRC | 7478a | NA | NA | NA | All-cause mortality | — | — |
| Tsoi KK et al. 2018 (48) | China | Case-control study | CRCd | 612 509a | NA | NA | NA | CRC-specific mortality, all-cause mortality, GIB/CVD/CBVD-related mortality | — | — |
| Ventura L et al. 2018 (49) | Italy | Cohort study | CRCd | 22 7011a | NA | NA | NA | CRC-specific mortality, all-cause mortality, CVD/major bleeding-related mortality | — | — |
| Sung JJY et al. 2019 (50) | China | Cohort study | CRCd | 13 528a | NA | NA | NA | CRC-specific mortality, all-cause mortality, CVD/CBVD-related mortality | — | — |
a
Participants were both male and female. AJCC = American Joint Committee on Cancer; CBVD = cerebrovascular diseases ; CC = colon cancer; CRC = colorectal cancer; CTS = California Teachers Study; CVD = cardiovascular diseases; DFS = disease-free survival; GIB = gastrointestinal bleeding; HPFS = Health Professionals Follow-up Study; NA = not available; NHS = Nurses’ Health Study; PFS = progression-free survival; RC = rectal cancer; RFS = recurrence-free survival; SOCCS = Study of Colorectal Cancer in Scotland .
b
Participants were female only.
c
Conference abstract only.
d
Studies report the subgroup result regarding the anatomical site of CRC (CC and RC).
Note: “—” represents data not available.