Table 1.

General characteristics of included studies

Study	Study Design	Case N	Control N	Male N	Female N	Age Range	Colon Cancer N	Rectal Cancer N	Total N
CCFR	Case-control	1163	977	1072	1068	20–81	445	286	2140
Colo 2&3	Case-control	87	125	117	95	38–86	59	27	212
DACHS	Case-control	2376	2206	2752	1830	33–99	1422	949	4582
DALS	Case-control	1116	1174	1261	1029	28–79	1112	0	2290
HPFS	Nested case- control	173	230	403	0	48–81	113	41	403
MEC	Nested case- control	328	346	361	313	45–76	241	81	674
NHS	Nested case- control	375	955	0	1330	44–69	285	86	1330
PHS	Nested case- control	375	389	764	0	40–85	286	84	764
PLCO	Nested case- control	486	415	518	383	55–75	320	161	901
PMH-CCFR	Case-control	280	122	0	402	48–73	206	64	402
OFCCR	Case-control	650	522	562	610	29–77	433	197	1172
VITAL	Nested case- control	285	288	300	273	50–76	215	66	573
WHI	Nested case- control	1466	1531	0	2997	50–79	1149	261	2997
Total		9160	9280	8110	10330	20–99	6286	2303	18440