Insulin-like growth factor-1, insulin-like growth factor binding protein-3 and lobule type in the Nurses' Health Study II

Table 2 Predominant type 1/no type 3 lobules according to batch-specific quartiles of plasma IGF-1

	IGF-1 (ng/ml)
	Quartile 1	Quartile 2	Quartile 3	Quartile 4	P value
Predominant type 1, no type 3/other lobule type (n)	(24/93)	(20/98)	(20/98)	(10/109)
Age and batch-adjusted^a	1 (reference)	0.82 (0.40 to 1.67)	0.84 (0.41 to 1.76)	0.37 (0.15 to 0.89)	0.01
Multivariate model 1^b	1 (reference)	0.98 (0.46 to 2.07)	1.06 (0.49 to 2.29)	0.47 (0.19 to 1.17)	0.08
Multivariate model 2^c	1 (reference)	0.94 (0.44 to 2.01)	1.00 (0.46 to 2.19)	0.41 (0.16 to 1.04)	0.05
Multivariate model 3^d	1 (reference)	0.92 (0.41 to 2.05)	0.98 (0.41 to 2.31)	0.39 (0.13 to 1.18)	0.07

Data (vs. other types) from the Nurses' Health Study II presented as odds ratio (95% confidence interval) unless stated otherwise. ^aAge at biopsy (continuous), insulin-like growth factor 1 (IGF-1) batch. ^bAge at biopsy (continuous), IGF-1 batch, body mass index (continuous), menopausal status (premenopausal/dubious; postmenopausal, no postmenopausal hormone use; postmenopausal, postmenopausal hormone use), histological category of benign breast disease (proliferative without atypia, proliferative with atypia). ^cMultivariate model 1 plus parity (nulliparous, parous), alcohol (none, < 1.5, 1.5 to 4.5, 4.5+ g/day). ^dMultivariate model 2 plus insulin-like growth factor binding protein-3 (continuous).

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