Table 2.

Distribution of chronotype and breast cancer risk factor characteristics, by case-control status among 39686 California Teacher Study (CTS) participants.

Characteristica	Case control status				All
	Non-case		Case
	N	%	N	%	N	%	p value
All	36967	100	2719	100	39686	100
Chronotype							0.002
Definite morning type	14220	38	955	35	15175	38
More morning than evening type	7678	21	563	21	8241	21
Neither morning/evening type	4923	13	385	14	5308	13
More evening than morning type	5511	15	424	16	5935	15
Definite Evening type	4635	13	392	14	5027	13
Age							<0.001
40-49 years	686	2	33	1	719	2
50-59 years	6423	17	283	10	6706	17
60-69 years	15562	42	969	36	16531	42
70-79 years	9605	26	963	35	10568	27
80-89 years	4691	13	471	17	5162	13
Race/Ethnicityb							0.049
White	32316	87	2422	89	34738	88
Black	810	2	55	2	865	2
Hispanic	1525	4	82	3	1607	4
Asian/Pacific Islander	1486	4	105	4	1591	4
Other	830	2	55	2	885	2
Smoking pack-yearsb							<0.001
Never smokers	24731	67	1667	61	26398	67
≤10	6517	18	500	18	7017	18
11-20	2156	6	189	7	2345	6
21-30	1172	3	103	4	1275	3
≥31	1229	3	152	6	1381	3
Unknown	1162	3	108	4	1270	3
BMI (kg/m2)							0.011
15-24	17780	48	1236	45	19016	48
25-29	10585	29	841	31	11426	29
30-54.8	6826	18	492	18	7318	18
Unknown	1776	5	150	6	1926	5
Alcohol consumption (g/day) b							<0.001
None	10992	30	755	28	11747	30
<20	21744	59	1580	58	23324	59
≥20	2938	8	282	10	3220	8
Unknown	1293	3	102	4	1395	4
Physical activity (hours per week) d							<0.001
0 to < 2.25	11226	30	951	35	12177	31
2.25 to < 5.50	12430	34	915	34	13345	34
5.50 to 24.00	13216	36	846	31	14062	35
Unknown	95	0	7	0	102	0
Family history of breast cancerc							<0.001
No	29867	81	2009	74	31876	80
Yes	6113	17	626	23	6739	17
Unknown	987	3	84	3	1071	3
Age at menarche (years)b							0.307
≤11	8546	23	669	25	9215	23
12-13	20978	57	1499	55	22477	57
≥14	7017	19	519	19	7536	19
Unknown/Never	426	1	32	1	458	1
Age at 1st full-term pregnancy (years) b							0.650
No full-term pregnancy	8420	23	625	23	9045	23
≤24	9967	27	710	26	10677	27
25-29	11301	31	864	32	12165	31
≥30	6758	18	485	18	7243	18
Unknown	521	1	35	1	556	1
Breast feeding history (months) b							0.031
Never pregnant	6328	17	468	17	6796	17
Pregnancy, but no live birth	2055	6	155	6	2210	6
0	5311	14	452	17	5763	15
>0 and <6	6148	17	461	17	6609	17
6-11	5445	15	373	14	5818	15
≥12	11028	30	769	27	11797	30
Unknown	652	2	41	2	693	2
Age at menopause (years)							0.063
< 40	2919	8	188	7	3107	8
40-49	9810	27	776	29	10586	27
50-54	11903	32	831	31	12734	32
55-59	4818	13	346	13	5164	13
60-70	623	2	45	2	668	2
Unknown	6894	19	533	20	7427	19
Hormone therapy (HT) usee							<0.001
Never	13010	35	825	30	13835	35
Ever	23920	65	1891	70	25811	65
Unknown	37	0	3	0	40	0

^aUnless otherwise noted, covariate assessment was based on the CTS Q5 survey

^bAssessment based on the CTS baseline survey

^cAssessment based on reporting family history (in a first degree relative) on any of the CTS surveys from baseline through the Q4 survey

^eAssessment based on ever reporting use of HT on any of the CTS surveys from baseline through the Q5 survey

^dAverage strenuous and moderate physical activity during past three years as reported on Q5 survey