Table 2. Association between menstrual and reproductive characteristics and gastric and colorectal cancer risk.

			GASTRIC CANCER						COLORECTAL CANCER
										COLON CANCER						RECTAL CANCER
Variablea		controls	cases	ORb	95% CI			p-val	controls	cases	ORb	95% CI			p-val	cases	ORb	95% CI			p-val	P-int.c
Premenopausal status		340	17	0.94	0.45	-	2.00	0.882	456	39	0.65	0.41	-	1.03	0.068	29	0.82	0.47	-	1.45	0.500	0.494
Nulliparity		235	22	1.12	0.65	-	1.92	0.682	278	43	0.78	0.53	-	1.13	0.184	27	0.95	0.60	-	1.50	0.824	0.464
Parous women
	Age at first birth (years)
	<25	369	58	1.00					437	126	1.00					80	1.00
	25–29	409	31	0.52	0.32	-	0.86	0.010	533	129	0.84	0.63	-	1.13	0.242	58	0.62	0.43	-	0.90	0.013
	>29	273	16	0.52	0.28	-	0.97	0.040	346	64	0.79	0.55	-	1.14	0.207	30	0.63	0.39	-	1.00	0.052
	Five-year trend*			0.69	0.53	-	0.90	0.006			0.95	0.82		1.10	0.473		0.95	0.78		1.14	0.556	0.978
	No. of children
	1–2	716	55	1.00					902	190	1.00					99	1.00
	3–4	279	39	1.27	0.78	-	2.04	0.337	350	103	0.96	0.72	-	1.29	0.810	58	1.11	0.77	-	1.62	0.574
	> 4	61	12	1.77	0.82	-	3.82	0.144	72	28	1.09	0.66	-	1.80	0.743	12	0.99	0.50	-	1.96	0.977
	Trend per child*			1.13	0.96	-	1.33	0.145			1.04	0.94		1.15	0.454		0.97	0.85		1.11	0.703	0.394
	Lactation first child (months)
	None	185	23	1.40	0.80	-	2.48	0.241	241	58	1.04	0.72	-	1.48	0.841	34	1.29	0.82	-	2.02	0.274
	1–6	542	43	1.00					682	141	1.00					67	1.00
	>6	177	28	1.53	0.89	-	2.65	0.126	217	80	1.26	0.89	-	1.77	0.192	44	1.43	0.93	-	2.21	0.105
	Six-month trend*			1.10	0.89	-	1.35	0.385			1.10	0.95		1.26	0.199		1.09	0.92		1.30	0.294	0.987
No. of miscarriages
	None	985	99	1.00					1231	301	1.00					147	1.00
	One or more	308	29	1.21	0.76	-	1.93	0.416	374	63	0.75	0.55	-	1.03	0.073	49	1.23	0.86	-	1.76	0.246	0.089
Age at menarche (years)
	<12	254	24	1.25	0.72	-	2.16	0.430	320	70	1.15	0.83	-	1.61	0.400	33	0.94	0.61	-	1.46	0.791
	12–13	599	46	1.00					749	144	1.00					82	1.00
	>13	433	56	1.26	0.81	-	1.96	0.298	523	146	1.17	0.89	-	1.53	0.267	80	1.15	0.81	-	1.61	0.438
	Trend per year*			1.05	0.94	-	1.17	0.397			1.01	0.94		1.09	0.713		1.07	0.97	-	1.17	0.155	0.319
Hormonal contraception use
	Never	668	101	1.00					809	254	1.00					135	1.00
	Ever	625	27	0.42	0.26	-	0.69	0.001	796	110	0.64	0.48	-	0.86	0.003	61	0.61	0.43	-	0.88	0.009	0.820
	< = 5 years	255	16	0.62	0.34	-	1.13	0.121	315	47	0.69	0.48	-	1.00	0.052	27	0.68	0.42	-	1.09	0.108
	>5 years	191	5	0.26	0.10	-	0.67	0.006	249	30	0.59	0.38	-	0.92	0.020	16	0.53	0.30	-	0.95	0.034
	Not known	179	6	0.31	0.13	-	0.75	0.009	232	33	0.63	0.41	-	0.97	0.036	18	0.60	0.35	-	1.04	0.069
Postmenopausal women
Age at menopause (years)
	< = 45	208	17	0.68	0.35	-	1.33	0.260	245	57	0.81	0.55	-	1.19	0.283	40	1.15	0.72	-	1.84	0.567
	46–49	226	31	1.07	0.60	-	1.92	0.821	259	78	1.02	0.71	-	1.47	0.902	32	0.87	0.53	-	1.44	0.595
	50–52	238	31	1.00					294	90	1.00					45	1.00
	>52	167	15	0.70	0.36	-	1.39	0.312	212	64	0.92	0.63	-	1.34	0.661	29	0.83	0.50	-	1.38	0.464
	Five-year trend*			0.92	0.75	-	1.14	0.451			1.00	0.87	-	1.13	0.947		0.99	0.83	-	1.18	0.910	0.955
Fertility time (years)
	<33	202	28	1.00					236	73	1.00					36	1.00
	33–36	233	23	0.75	0.40	-	1.41	0.371	269	82	0.98	0.67	-	1.43	0.916	46	1.09	0.68	-	1.77	0.715
	37–39	213	22	0.75	0.40	-	1.43	0.386	263	69	0.83	0.56	-	1.22	0.340	33	0.79	0.47	-	1.32	0.366
	>39	185	19	0.82	0.43	-	1.59	0.565	233	64	0.82	0.55	-	1.23	0.340	30	0.77	0.45	-	1.31	0.333
	Five-year trend*			0.91	0.75	-	1.12	0.379			0.99	0.87	-	1.12	0.871		0.94	0.80	-	1.11	0.463	0.588
Hormone therapy use
	Never	858	105	1.00					1025	311	1.00					159	1.00
	Ever	95	6	0.63	0.26	-	1.53	0.306	124	14	0.44	0.24	-	0.78	0.005	8	0.51	0.24	-	1.07	0.075	0.743

^a Totals do not add up because of missing values.

^b Odds ratios (ORs) and 95% confidence intervals (95% CI) adjusted for age, educational level, BMI 1-year prior to the interview, family history of gastric/colorectal cancer, tobacco, hormone therapy use and hormonal contraception use (the latter two variables were excluded as confounders when analyzing their association with gastric and colorectal cancer risk). Province was included as a random effect term.

^c P-int.: P value of the interaction term between tumor subsite and the corresponding variable.

* In italics: ORs, 95% CI and P values obtained with the corresponding variable as a continuous term.