Physical Activity and Postmenopausal Breast Cancer Risk in the NIH-AARP Diet and Health Study

Tricia M. Peters; Arthur Schatzkin; Gretchen L. Gierach; Steven C. Moore; James V. Lacey; Nicholas J. Wareham; Ulf Ekelund; Albert R. Hollenbeck; Michael F. Leitzmann

doi:10.1158/1055-9965.EPI-08-0768

DOI: 10.1158/1055-9965.EPI-08-0768 Published January 2009

Article Figures & Data

Tables

Table 1.

Characteristics of the study population by level of physical activity at baseline, 182,862 postmenopausal women, NIH-American Association of Retired Persons Diet and Health Study (1995-1996)

Characteristics	Total	Physical activity (times per week)
Characteristics	Total			Inactive	<1	1-2	3-4	≥5
Participants, n (%)	182,862	41,580 (22.7)	26,311 (14.4)	38,713 (21.2)	46,251 (25.3)	30,007 (16.4)
Age at baseline (y)	62.1	62.4	61.3	61.8	62.4	62.5
BMI (kg/m²)	26.9	28.6	27.6	26.9	26.0	25.3
Race/ethnicity (%)
White	89.9	88.5	90.2	90.6	90.0	90.8
Black	5.5	6.6	5.6	5.0	5.3	4.9
Hispanic	1.9	2.3	1.8	1.8	1.9	1.5
Asian/Pacific Islander/Native American	1.5	1.4	1.3	1.5	1.7	1.6
College education (%)	29.6	21.6	28.5	31.0	33.1	34.2
Family history of breast cancer* (%)	12.4	12.0	12.6	12.5	12.5	12.4
Current smoker (%)	14.4	19.7	17.6	14.8	10.6	9.6
Current MHT use (%)	44.9	37.8	45.3	46.0	48.9	47.0
Age at menarche (y)	12.51	12.46	12.48	12.50	12.53	12.55
Age at first birth in parous women (y)	22.88	22.68	22.78	22.94	23.02	22.97
Parity (no. children)	2.01	2.02	2.01	2.00	2.02	1.99
Age at menopause (y)	46.88	46.46	46.76	46.91	47.11	47.21
Alcohol intake (g/d)	6.0	5.8	6.1	5.8	6.1	6.3
Total energy intake^† (kcal/d)	1,597.4	1,623.5	1,557.3	1,583.2	1,576.1	1,647.4

NOTE: All values, except age, are adjusted for age.
↵* Family history of breast cancer in a first-degree female relative.
↵† Adjusted for total energy intake.

Table 2.

RR (95% CI) for the association between physical activity and postmenopausal breast cancer incidence among 182,862 postmenopausal women

Physical activity (times per week)	Person-years	No. cases	Age-adjusted RR (95% CI)	Multivariate RR* (95% CI)	Multivariate RR^† (95% CI)
Inactive	285,349	1,485	1.0 (Reference)	1.0 (Reference)	1.0 (Reference)
<1	184,682	981	1.04 (0.96-1.13)	0.99 (0.91-1.07)	1.00 (0.92-1.08)
1-2	271,497	1,391	0.99 (0.92-1.07)	0.94 (0.87-1.01)	0.96 (0.89-1.03)
3-4	325,701	1,711	1.01 (0.94-1.08)	0.93 (0.87-1.00)	0.97 (0.90-1.04)
≥5	211,557	1,041	0.94 (0.87-1.02)	0.87 (0.81-0.95)	0.92 (0.85-1.00)
P_trend			0.13	<0.001	0.04

↵* Multivariate models used age as the underlying time metric and were adjusted for race/ethnicity (White, Black, Hispanic, Asian/Pacific Islander/American Indian), education level (<12 years or high school equivalent, 12 years or high school equivalent, post-high school vocational or technical training, some college, college graduate, postgraduate), smoking status (nonsmoker, former, current), family history of breast cancer (no, yes), menopausal hormone use (never, current, past), age at first birth (nulliparous, <20, 20-24, 25-29, ≥30 years), age at menarche (<13, 13-14, ≥15 years), age at menopause (<40, 40-44, 45-49, 50-54, ≥55 years), parity (number of children: 0, 1-2, ≥3), and alcohol intake (g/d; quintiles adjusted for total energy intake).
↵† Additionally adjusted for BMI (<25.0, 25.0-29.9, 30.0-34.9, ≥35.0 kg/m²).

Table 3.

Multivariate RR (95% CI) for the association between physical activity and breast cancer incidence among postmenopausal women according to selected tumor characteristics

Tumor characteristics*	No. cases	Physical activity (times per week)							P_trend	P_{heterogeneity}
Tumor characteristics*	No. cases			Inactive	<1	1-2	3-4	≥5	P_trend	P_{heterogeneity}
Hormone receptor status
ER+	2,083	1.0 (Reference)	1.03 (0.89-1.19)	0.95 (0.83-1.08)	0.98 (0.86-1.11)	0.97 (0.84-1.12)	0.64	0.07
ER−	411	1.0 (Reference)	1.10 (0.81-1.49)	0.85 (0.63-1.14)	0.85 (0.64-1.12)	0.75 (0.54-1.04)	0.03

ER+/PR+	1,649	1.0 (Reference)	1.00 (0.84-1.18)	0.97 (0.84-1.13)	0.96 (0.83-1.11)	0.96 (0.82-1.13)	0.53
ER+/PR−	338	1.0 (Reference)	1.29 (0.90-1.84)	0.93 (0.65-1.32)	1.17 (0.85-1.60)	1.05 (0.73-1.51)	0.85
ER−/PR+	48	1.0 (Reference)	1.10 (0.41-2.95)	1.15 (0.47-2.78)	1.29 (0.56-2.95)	0.62 (0.21-1.86)	0.56	0.37
ER−/PR−	359	1.0 (Reference)	1.10 (0.80-1.53)	0.84 (0.61-1.15)	0.81 (0.60-1.10)	0.78 (0.55-1.10)	0.05
Unknown ER or PR	3,039	1.0 (Reference)	0.90 (0.80-1.02)	0.95 (0.85-1.06)	0.92 (0.83-1.01)	0.81 (0.72-0.91)	0.002

Tumor stage
In situ	1,176	1.0 (Reference)	1.10 (0.91-1.33)	0.90 (0.75-1.08)	0.93 (0.78-1.10)	0.93 (0.77-1.13)	0.20	0.85
Invasive	5,433	1.0 (Reference)	0.97 (0.88-1.06)	0.95 (0.87-1.03)	0.94 (0.87-1.01)	0.86 (0.79-0.94)	0.001

Localized	3,158	1.0 (Reference)	0.97 (0.86-1.09)	0.95 (0.86-1.06)	1.00 (0.90-1.10)	0.85 (0.76-0.96)	0.04	0.17
Regional/distant	1,298	1.0 (Reference)	0.99 (0.83-1.17)	0.83 (0.71-0.98)	0.74 (0.63-0.86)	0.85 (0.71-1.01)	0.003	0.36^†
Tumor histology
Ductal	3,568	1.0 (Reference)	0.98 (0.88-1.10)	0.96 (0.87-1.06)	0.93 (0.84-1.02)	0.89 (0.80-0.99)	0.02
Lobular	550	1.0 (Reference)	1.24 (0.95-1.63)	0.92 (0.71-1.19)	0.89 (0.69-1.14)	0.87 (0.65-1.15)	0.05	0.41
Ductal-lobular	436	1.0 (Reference)	0.80 (0.58-1.12)	0.80 (0.60-1.08)	0.95 (0.73-1.24)	0.89 (0.66-1.20)	0.96

NOTE: Multivariate models used age as the underlying time metric and were adjusted for race/ethnicity (White, Black, Hispanic, Asian/Pacific Islander/American Indian), education level (<12 years or high school equivalent, 12 years or high school equivalent, post-high school vocational or technical training, some college, college graduate, postgraduate), smoking status (nonsmoker, former, current), family history of breast cancer (no, yes), menopausal hormone use (never, current, past), age at first birth (nulliparous, <20, 20-24, 25-29, ≥30 years), age at menarche (<13, 13-14, ≥15 years), age at menopause (<40, 40-44, 45-49, 50-54, ≥55 years), parity (number of children: 0, 1-2, ≥3), and alcohol intake (g/d; quintiles adjusted for total energy intake).
↵* Hormone receptor status and tumor histology limited to invasive cancers.
↵† P value for comparison of in situ, localized, and regional/distant.

Table 4.

Multivariate RR (95% CI) for the association between physical activity and breast cancer incidence among postmenopausal women according to BMI, MHT use, and family history of breast cancer

	No. cases	Physical activity (times per week)							P_trend	P_{heterogeneity}
	No. cases		Inactive	<1	1-2	3-4	≥5		P_trend	P_{heterogeneity}
BMI (kg/m²)
≥25.0	3,787	1.0 (Reference)	0.98 (0.89-1.08)	0.98 (0.90-1.08)	0.92 (0.84-1.01)	0.86 (0.77-0.96)	0.003	0.07
<25.0	2,822	1.0 (Reference)	1.01 (0.92-1.11)	0.97 (0.89-1.05)	0.99 (0.92-1.08)	0.95 (0.87-1.05)	0.64
MHT use
Ever use	4,073	1.0 (Reference)	1.03 (0.93-1.15)	1.00 (0.90-1.10)	1.00 (0.92-1.10)	0.97 (0.88-1.08)	0.34	0.002
Never use	2,528	1.0 (Reference)	0.95 (0.84-1.08)	0.88 (0.79-0.99)	0.86 (0.77-0.96)	0.76 (0.67-0.86)	<0.001
Family history
Family history	1,193	1.0 (Reference)	0.99 (0.83-1.19)	0.92 (0.78-1.08)	0.75 (0.64-0.89)	0.75 (0.62-0.91)	<0.001	0.003
No family history	5,124	1.0 (Reference)	0.99 (0.90-1.09)	0.95 (0.87-1.03)	0.98 (0.90-1.06)	0.88 (0.81-0.97)	0.03

NOTE: Multivariate models used age as the underlying time metric and were adjusted for race/ethnicity (White, Black, Hispanic, Asian/Pacific Islander/American Indian), education level (<12 years or high school equivalent, 12 years or high school equivalent, post-high school vocational or technical training, some college, college graduate, postgraduate), smoking status (nonsmoker, former, current), family history of breast cancer (no, yes), menopausal hormone use (never, current, past), age at first birth (nulliparous, <20, 20-24, 25-29, ≥30 years), age at menarche (<13, 13-14, ≥15 years), age at menopause (<40, 40-44, 45-49, 50-54, ≥55 years), parity (number of children: 0, 1-2, ≥3), and alcohol intake (g/d; quintiles adjusted for total energy intake).

Table 5.

Multivariate RR (95% CI) for the association between physical activity and breast cancer incidence among postmenopausal women according to joint effect of physical activity and BMI, joint effect of physical activity and MHT use, and joint effect of physical activity and family history of breast cancer

	No. cases	Physical activity (times per week)
	No. cases		Inactive	<1	1-2	3-4	≥5
BMI (kg/m²)
≥25.0	3,787	1.0 (Reference)	0.98 (0.89-1.08)	0.98 (0.90-1.08)	0.92 (0.84-1.01)	0.86 (0.77-0.96)
<25.0	2,822	0.84 (0.75-0.94)	0.85 (0.75-0.96)	0.76 (0.68-0.84)	0.84 (0.77-0.92)	0.80 (0.72-0.88)
MHT use
Ever use	4,073	1.0 (Reference)	1.03 (0.93-1.15)	1.00 (0.90-1.10)	1.01 (0.92-1.10)	0.97 (0.88-1.08)
Never use	2,528	0.79 (0.72-0.88)	0.76 (0.67-0.85)	0.70 (0.63-0.78)	0.68 (0.61-0.76)	0.60 (0.53-0.68)
Family history
Family history	1,193	1.0 (Reference)	0.99 (0.83-1.19)	0.92 (0.78-1.08)	0.75 (0.64-0.89)	0.75 (0.62-0.91)
No family history	5,124	0.57 (0.50-0.65)	0.57 (0.50-0.65)	0.54 (0.48-0.62)	0.56 (0.49-0.64)	0.51 (0.44-0.58)

NOTE: Multivariate models used age as the underlying time metric and were adjusted for race/ethnicity (White, Black, Hispanic, Asian/Pacific Islander/American Indian), education level (<12 years or high school equivalent, 12 years or high school equivalent, post-high school vocational or technical training, some college, college graduate, postgraduate), smoking status (nonsmoker, former, current), family history of breast cancer (no, yes), menopausal hormone use (never, current, past), age at first birth (nulliparous, <20, 20-24, 25-29, ≥30 years), age at menarche (<13, 13-14, ≥15 years), age at menopause (<40, 40-44, 45-49, 50-54, ≥55 years), parity (number of children: 0, 1-2, ≥3), and alcohol intake (g/d; quintiles adjusted for total energy intake).