Skip to main content
. Author manuscript; available in PMC: 2012 May 1.
Published in final edited form as: Cancer. 2010 Nov 10;117(9):1946–1956. doi: 10.1002/cncr.25728

Table 2.

Odds ratios for specifica histologic types of breast cancer by age at first full-term birth

Controls
(N=26,677)		 Ductal breast cancer
(N=18,329)		 Lobular breast cancer
(N=2,030)		 P-value
ductal
vs.
lobular		 Mixed ductal-lobular
breast cancer
(N=907)		 P-value
Mixed
vs.
lobular
Age at first birth N N OR (95% CI) N OR (95% CI) N OR (95% CI)
Nulliparous 3,172 2,548 1.19 (1.08–1.31) 247 1.72 (1.34–2.20) 0.004 111 1.09 (0.77–1.54) 0.03
<20 4,323 2,516 1 234 1.00 121 1
20–24 11,476 7,298 1.07 (1.01–1.13) 790 1.25 (1.07–1.46) 0.05 330 0.99 (0.79–1.23) 0.08
25–29 5,534 4,118 1.22 (1.14–1.31) 796 1.71 (1.44–2.04) <0.001 232 1.36 (1.06–1.73) 0.12
30+ 2,172 1,849 1.31(1.20–1.43) 263 2.38 (1.94–2.93) <0.001 113 1.55 (1.15–2.07) 0.01
P-trend (per 1 year)c <0.001 <0.001 <0.001
5-Year increment 1.11 (1.08–1.14) 1.32 (1.24–1.40) 1.23 (1.12–1.34)
a

Includes ductal, lobular, and mixed ductal-lobular only (other histologic subtypes were excluded from analysis (N=1577)). Odds ratios are adjusted for age, state of residence, study period, parity, age of menarche, menopausal status, age at menopause, postmenopausal hormone use, oral contraceptive use, family history of breast cancer, recent alcohol consumption, body mass index, history of mammographic screening, and education.

b

P-trend calculated among parous women only.