Mammographic density. Potential mechanisms of breast cancer risk associated with mammographic density: hypotheses based on epidemiological evidence

Table 2 Studies of pituitary hormones, related growth factors, and mammographic density

			Direction of association [ref.]
Hormone	Number of studies^a	Menopausal status	Positive	None	Inverse
Growth hormone	1	Premenopausal		Boyd et al. [31]¹
		Postmenopausal		Boyd et al. [31]¹
Prolactin	4	Premenopausal	Boyd et al. [31] (dense area only)
		Postmenopausal	Boyd et al. [31], Greendale et al. [34]	Tamimi et al. [27]¹, Bremnes et al. [39]
IGF-I	7	Premenopausal	Boyd et al. [31], Byrne et al. [35], Diorio et al. [36]	Maskarinec et al. [37], dos Santo Silva et al. [38]
		Postmenopausal	Bremnes et al. [39]	Aiello et al. [28]^b,c, Boyd et al. [31], Byrne et al. [35], Diorio et al. [36]¹, dos Santo Silva et al. [38]
IGFBP-3	7	Premenopausal		Boyd et al. [31], Byrne et al. [35], Maskarinec et al. [37], dos Santos Silva et al. [38]	Diorio et al. [36]
		Postmenopausal		Aiello et al. [28]^b,c, Boyd et al. [31], Byrne et al. [35], dos Santos Silva et al. [38]², Bremnes et al. [39]
IGF-I/IGFBP-3 ratio	7	Premenopausal	Boyd et al. [31], Byrne et al. [35], Maskarinec et al. [37]	Diorio et al. [36]¹, dos Santos Silva et al. [38]
		Postmenopausal	Bremnes et al. [39]	Aiello et al. [28]^b, Boyd et al. [31], Byrne et al. [35], Diorio et al. [36]¹, dos Santos Silva et al. [38]	Aiello et al. [28]^c

Associations shown are for percentage density, unless otherwise indicated. Associations were classified as positive, none, or inverse according to the direction of effect and the statistical significance of the values after adjustment for other factors, using a criterion of P < 0.05. Several associations were statistically significant before adjustment for other factors and these are indicated as follows: ¹positive association before adjustment and ²inverse association before adjustment. ^aSome studies included both premenopausal and postmenopausal women. ^bResults for never users of hormones. ^cResults for users of hormones. IGF, insulin-like growth factor; IGFBP, insulin-like growth factor binding protein.

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