Reproductive factors and the risk of triple-negative breast cancer in white women and African-American women: a pooled analysis

Huiyan Ma; Giske Ursin; Xinxin Xu; Eunjung Lee; Kayo Togawa; Lei Duan; Yani Lu; Kathleen E. Malone; Polly A. Marchbanks; Jill A. McDonald; Michael S. Simon; Suzanne G. Folger; Jane Sullivan-Halley; Dennis M. Deapen; Michael F. Press; Leslie Bernstein

doi:10.1186/s13058-016-0799-9

Table 2 Multivariable adjusted odds ratio (OR) and 95% confidence interval (CI) for ER/PR/HER2-defined subtypes of breast cancer associated with reproductive factors

From: Reproductive factors and the risk of triple-negative breast cancer in white women and African-American women: a pooled analysis

	Controls	Triple-negative		Luminal A-like		Luminal B-like		HER2-enriched
	N	N	OR (95% CI)	N	OR (95% CI)	N	OR (95% CI)	N	OR (95% CI)
All women
Age at menarche, years
≤ 12	1292	289	1.00	820	1.00	186	1.00	110	1.00
13	634	158	1.13 (0.90–1.41)	419	0.98 (0.84–1.16)	99	1.06 (0.81–1.40)	66	1.22 (0.88–1.69)
≥ 14	522	107	0.89 (0.69–1.14)	278	0.77 (0.64–0.92)	75	0.92 (0.68–1.24)	51	1.07 (0.75–1.53)
Trend P value			0.55		0.009		0.70		0.56
P value for homogeneity of trends			0.19
Number of completed pregnancies
Never pregnant	250	68	1.00	224	1.00	56	1.00	31	1.00
Any completed pregnancies	1990	431	0.91 (0.67–1.24)	1104	0.79 (0.64–0.98)	263	0.82 (0.58–1.15)	176	0.78 (0.50–1.20)
1	399	98	0.95 (0.66–1.36)	277	0.92 (0.71–1.19)	84	1.17 (0.79–1.74)	50	1.02 (0.62–1.67)
2	709	168	0.98 (0.70–1.37)	438	0.81 (0.64–1.02)	109	0.88 (0.61–1.29)	59	0.69 (0.42–1.11)
≥3	882	165	0.84 (0.60–1.19)	389	0.64 (0.50–0.81)	70	0.53 (0.35–0.80)	67	0.65 (0.40–1.05)
Trend P value			0.26		<0.0001		<0.0001		0.02
P value for homogeneity of trends			0.09
Only non-completed pregnancy	208	55	0.91 (0.60–1.38)	189	1.02 (0.76–1.35)	41	0.88 (0.55–1.39)	20	0.69 (0.38–1.26)
Parous women only^a,b
Age at first completed pregnancy, years
≤20	799	165	1.00	297	1.00	69	1.00	62	1.00
21–24	510	107	1.03 (0.78–1.38)	274	1.22 (0.98–1.52)	63	1.18 (0.80–1.73)	43	1.05 (0.68–1.62)
25–29	348	85	1.08 (0.77–1.52)	275	1.64 (1.28–2.10)	56	1.22 (0.78–1.89)	33	1.10 (0.66–1.85)
≥30	333	73	0.80 (0.54–1.20)	256	1.17 (0.88–1.55)	75	1.09 (0.68–1.74)	38	0.96 (0.55–1.70)
Trend P value			0.50		0.05		0.57		0.95
P value for homogeneity of trends			0.24
Duration of breastfeeding, months
Never	748	166	1.00	370	1.00	81	1.00	60	1.00
Ever	1242	264	0.80 (0.63–1.02)	732	0.78 (0.65–0.94)	182	0.89 (0.65–1.23)	116	0.91 (0.63–1.32)
< 6	541	134	0.96 (0.74–1.26)	303	0.83 (0.68–1.02)	82	0.99 (0.70–1.41)	35	0.68 (0.43–1.07)
6–11	263	40	0.55 (0.37–0.82)	165	0.76 (0.59–0.99)	35	0.70 (0.44–1.12)	33	1.28 (0.78–2.09)
≥ 12	438	90	0.69 (0.50–0.96)	264	0.71 (0.56–0.90)	65	0.85 (0.56–1.30)	48	1.10 (0.69–1.75)
Trend P value			0.006		0.004		0.28		0.36
P value for homogeneity of trends			0.08

Models in multivariate analysis included sub-study (the Women’s CARE Study or the Women’s BCIS Study, the Women’s LIFE Study), study site (Los Angeles, Detroit), race (white, African-American), reference age (in 5-year age categories), education (≤ high school, technical school or some college, college graduate), first-degree breast cancer family history (no, yes), body mass index (<25, 25–29, ≥30 kg/m²), a variable combining menopausal status and hormone therapy use (premenopausal; postmenopausal: never used hormone therapy, ever used hormone therapy; unknown menopausal status), lifetime recreational physical activity (inactive, ≤2.2, 2.3–6.6, 6.7–15.1, ≥15.2 annual metabolic equivalents of energy expenditure, hour/week), alcohol intake (never, former, current), cigarette smoking status (never, former, current), age at menarche (≤12,13, ≥14 years), number of completed pregnancies (never pregnant, 1, 2, ≥3, only non-completed pregnancy), oral contraceptive use (never, <1, 1–4, 5–9, ≥10 years). ^aModels additionally included age at first completed pregnancy (≤20, 21–24, 25–29, ≥30 years) and duration of breastfeeding (never, <6, 6–11, ≥12 months). ^bAdditionally seven parous case participants who had missing information on breastfeeding were excluded. Triple negative = estrogen receptor (ER)–/progesterone receptor (PR)–/human epidermal growth factor receptor-2 (HER2)–, Luminal A-like = ER+ and/or PR+ plus HER2–, Luminal B-like = ER+ and/or PR+ plus HER2+, HER2-enriched = ER–/PR– /HER2 +

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