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

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

doi:10.1186/s13058-016-0799-9

Table 4 Multivariable adjusted odds ratio (OR) and 95% confidence interval (CI) for ER/PR/HER2-defined subtypes of breast cancer associated with reproductive factors by age

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

	Younger (20–44 years)					Older^a (45–64 years)
	Controls	Triple-negative		Luminal A-like		Controls	Triple-negative		Luminal A-like
	N	N	OR (95% CI)	N	OR (95% CI)	N	N	OR (95% CI)	N	OR (95% CI)
All women
Age at menarche, years
≤12	491	139	1.00	299	1.00	801	150	1.00	521	1.00
13	252	94	1.35 (0.98–1.85)	152	0.94 (0.72–1.22)	382	64	0.90 (0.65–1.25)	267	0.94 (0.77–1.16)
≥14	227	58	0.86 (0.60–1.23)	98	0.63 (0.47–0.85)	295	49	0.85 (0.59–1.22)	180	0.85 (0.67–1.08)
Trend P value			0.72		0.004			0.33		0.18
P-value for homogeneity of trends				0.06					0.92
Number of completed pregnancies
Never pregnant	115	47	1.00	91	1.00	135	21	1.00	133	1.00
Any completed pregnancies	735	207	0.88 (0.58–1.32)	368	0.75 (0.54–1.05)	1255	224	1.06 (0.64–1.77)	736	0.82 (0.62–1.09)
1	193	48	0.75 (0.46–1.23)	107	0.83 (0.56–1.23)	206	50	1.30 (0.73–2.31)	170	1.01 (0.72–1.42)
2	289	83	0.94 (0.60–1.48)	159	0.82 (0.57–1.19)	420	85	1.15 (0.67–1.96)	279	0.80 (0.59–1.09)
≥ 3	253	76	0.98 (0.61–1.56)	102	0.59 (0.40–0.88)	629	89	0.85 (0.49–1.48)	287	0.70 (0.51–0.96)
Trend P value			0.73		0.02			0.13		0.006
P value for homogeneity of trends				0.03					0.83
Only non-completed pregnancy	120	37	0.91 (0.54–1.53)	90	1.03 (0.68–1.57)	88	18	1.08 (0.54–2.19)	99	1.10 (0.74–1.65)
Parous women only^b,c
Age at first completed pregnancy, years
≤ 20	235	71	1.00	85	1.00	564	94	1.00	212	1.00
21–24	142	43	1.02 (0.63–1.65)	80	1.44 (0.95–2.17)	368	64	1.05 (0.72–1.54)	194	1.11 (0.85–1.44)
25–29	168	50	0.94 (0.57–1.56)	99	1.48 (0.97–2.27)	180	35	1.20 (0.74–1.94)	176	1.84 (1.34–2.51)
≥30	190	42	0.62 (0.34–1.12)	102	1.15 (0.71–1.86)	143	31	1.08 (0.61–1.89)	154	1.32 (0.91–1.90)
Trend P value			0.15		0.52			0.60		0.01
P value for homogeneity of trends				0.07					0.27
Duration of breastfeeding, months
Never	204	64	1.00	100	1.00	544	102	1.00	270	1.00
Ever	531	142	0.75 (0.50–1.12)	266	0.70 (0.50–0.99)	711	122	0.85 (0.62–1.17)	466	0.83 (0.67–1.03)
< 6	209	69	0.93 (0.60–1.44)	97	0.72 (0.49–1.05)	332	65	0.97 (0.67–1.39)	206	0.90 (0.70–1.16)
6–11	126	22	0.49 (0.27–0.89)	64	0.68 (0.44–1.07)	137	18	0.62 (0.35–1.10)	101	0.84 (0.60–1.17)
≥ 12	196	51	0.60 (0.35–1.01)	105	0.68 (0.44–1.05)	242	39	0.79 (0.50–1.24)	159	0.71 (0.53–0.96)
Trend P value			0.02		0.12			0.17		0.03
P value for homogeneity of trends				0.32					0.93

Triple-negative = estrogen receptor (ER)–/progesterone receptor (PR)–/human epidermal growth factor receptor-2 (HER2)–, Luminal A-like = ER+ and/or PR+ plus HER2. 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, Africa-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), lifetime recreational physical activity (inactive, ≤2.2, 2.3–6.6, 6.7–15.1, ≥15.2 annual metabolic energy equivalents, 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). ^aAdditionally adjusted for a variable combining menopausal status and hormone therapy use (premenopausal; postmenopausal: never used hormone therapy, ever used hormone therapy; unknown menopausal status). ^bModels additionally included age at first completed pregnancy (≤20, 21–24, 25–29, ≥30 years) and duration of breastfeeding (never, <6, 6–11, ≥12 months). ^cAdditionally three younger case participants who had missing information on breastfeeding were excluded

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ISSN: 1465-542X

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