Table 1.

Distribution of Baseline Characteristics by Baseline Status of Hormone Therapy Use Among 56,864 Perimenopausal and Postmenopausal Participants in the California Teachers Study, 1995–2006

Characteristics	Total No.	Status of HT Use at Baseline (Estrogen, Estrogen + Progestin, or User of Mixed Formulations)
		Baseline-Never HT User	Baseline-Former HT User	Baseline-Recent HT User
No. of participants	56,864	13,778	8,653	34,433
No. of invasive colon cancer cases	442	151	98	193
Mean age at baseline, years (SD)		62.7 (9.2)	65.0 (8.8)	58.9 (8.5)
Menopausal status, %a
Perimenopausal	2,235	44.7	9.9	45.3
Postmenopausal, natural menopause	29,397	34.7	18.3	47.0
Postmenopausal, bilateral oophorectomy	8,851	4.2	12.1	83.6
Postmenopausal, other reason	16,381	13.5	12.0	74.5
Race/ethnicity, %a
White	50,746	23.2	15.2	61.6
African American	1,609	38.8	19.0	42.1
Otherb	4,509	30.1	14.1	55.7
Long-term recreational physical activity, %a,c
Low (<0.5 hour/week of any activity)	8,920	27.0	15.7	57.3
Intermediate	28,614	21.8	14.0	64.3
High (≥3 hours/week of any activity)	18,963	24.4	14.4	61.3
Body mass index, kg/m2a
<25	30,578	21.0	13.2	65.7
25–29	15,300	23.6	15.4	61.0
≥30	8,378	29.6	15.9	54.6
Regular NSAID usea,d
Low	49,058	23.9	14.3	61.9
High	5,944	18.8	14.8	66.4
Calcium intake, mga,e
≤696.8	25,944	24.1	15.5	61.4
>696.8	25,945	22.2	13.8	64.0
Calcium, mg, + vitamin D, IU, intakea,f
Low	44,377	23.5	14.2	62.3
High	7,512	20.8	14.0	65.3
Family history of colorectal cancera,g
No	49,073	23.3	14.2	62.5
Yes	6,174	24.4	16.1	59.5
Personal history of colorectal polypsa,h
No	51,425	23.6	14.2	62.3
Yes	3,822	21.0	18.1	61.0
Smoking historya,i
Never smoker	33,035	24.4	14.0	61.6
Former smoker	19,878	20.9	14.8	64.3
Current smoker	3,631	30.0	15.4	55.0
Alcohol intake, g/daya,j
0	17,520	27.9	15.4	56.7
<20	31,240	21.2	13.6	65.2
≥20	5,516	22.0	14.5	63.5

Abbreviations: HT, hormone therapy; NSAID, nonsteroidal antiinflammatory drug; SD, standard deviation.

^aAll percentages, except those for race/ethnicity and menopausal status, are age standardized by 5-year age categories to the age distribution of the analytical cohort; the numbers of missing and unknown participants are not shown in the table.

^b“Other” includes Hispanic, Asian, Native American, mixed, or none reported.

^cLong-term recreational physical activity combines strenuous and moderate activity and is defined as low, intermediate, or high average weekly hours of long-term recreational physical activity.

^dRegular NSAID use combines information on aspirin and ibuprofen use. High NSAID use was defined as use ≥4 times per week for more than 4 years; low/no regular NSAID use included all others.

^eCalcium intake (mg) from diet and supplements was cut at the median value for participants in this analysis, 696.8 mg/day.

^fCalcium intake plus vitamin D intake (from diet and supplements) was dichotomized as the highest quartile for both calcium and vitamin D versus all others.

^gA positive family history of colorectal cancer was defined as colon or rectal cancer in at least 1 first-degree relative (mother, father, sister, or brother).

^hSelf-reported personal history of colon or rectal polyps (not cancer) was categorized as no, yes, or unknown.

ⁱSmoking history was categorized as never, former, or current smoker.

^jAlcohol intake was categorized as 0 g/day, <20 g/day, or ≥20 g/day.