Early pregnancy sex steroids during primiparous pregnancies and maternal breast cancer: a nested case–control study in the Northern Sweden Maternity Cohort

Table 3 Early pregnancy endogenous hormones and breast cancer risk for a doubling of hormone concentration, by ER/PR status: Northern Sweden Maternity Cohort

	Overall	ER–/PR–	ER+/PR+	p _het
Estradiol	220/404	50/89	152/282
Estradiol	1.19 (0.94–1.50)	1.35 (0.78–2.32)	1.08 (0.81–1.43)	0.18
Free estradiol	210/374	49/86	143/258
Free estradiol	1.02 (0.80–1.29)	1.09 (0.59–2.02)	0.95 (0.72–1.27)	0.31
Estrone	222/410	50/90	154/286
Estrone	1.08 (0.89–1.30)	1.20 (0.77–1.88)	0.97 (0.78–1.22)	0.13
Testosterone	221/407	50/90	153/283
Testosterone	1.33 (1.02–1.74)	0.82 (0.47–1.43)	1.57 (1.13–2.18)	0.05
Free testosterone	211/377	49/87	144/260
Free testosterone	1.08 (0.88–1.33)	0.66 (0.40–1.08)	1.31 (1.02–1.68)	<0.01
Progesterone	221/406	50/90	153/282
Progesterone	0.94 (0.67–1.34)	1.61 (0.77–3.36)	0.64 (0.41–1.00)	0.01
SHBG	212/384	49/89	145/264
SHBG	1.19 (0.95–1.50)	1.47 (0.90–2.40)	1.05 (0.80–1.38)	0.10

Data presented as number of cases/controls and OR_log2 (95% CI)
Conditional logistic regression controlling for gestational age at blood collection (continuous). p _het between ER+/PR+ and ER–/PR– breast cancer subtypes assessed using a likelihood ratio test comparing models assuming the same association between the hormones and breast cancer overall to one assuming different associations by subtype
CI confidence interval, ER estrogen receptor, OR odds ratio, PR progesterone receptor, SHBG sex hormone binding globulin

ISSN: 1465-542X