The combined influence of multiple sex and growth hormones on risk of postmenopausal breast cancer: a nested case-control study

Table 4 Risk of breast cancer among postmenopausal women not using hormones in the Nurses' Health Study by several mammotropic hormone scores^a among 182 cases and 370 controls

	RR (95% CI)^b
Mammotropic hormone score	Cases/controls, n	Sex hormones and prolactin	Cases/controls, n	Adding IGF-1 and c-peptide
Number of hormones > geometric mean^c
0 or 1	20/65	1.0	8/40	1.0
2 or 3	25/90	0.9 (0.5 to 1.8)	25/74	1.7 (0.7 to 4.1)
4 or 5	52/99	1.6 (0.9 to 3.0)	36/92	1.9 (0.8 to 4.5)
6 or 7	64/87	2.3 (1.2 to 4.2)	64/92	3.2 (1.4 to 7.3)
8+	21/29	2.2 (1.0 to 4.9)	49/72	3.2 (1.4 to 7.5)
Per 1-unit increase	182/370	1.17 (1.07 to 1.26)	182/370	1.15 (1.06 to 1.23)
Per 1 SD increase^c	182/370	1.44 (1.19 to 1.75)	182/370	1.38 (1.16 to 1.66)
P trend	182/370	< 0.001	182/370	< 0.001
Score weighted by individual hormone associations^d,e
Quintile 1	42/134	1.0	20/74	1.0
Quintile 2	43/100	1.3 (0.8 to 2.2)	27/74	1.3 (0.7 to 2.6)
Quintile 3	40/71	1.8 (1.0 to 3.0)	35/74	1.7 (0.9 to 3.2)
Quintile 4	34/39	2.7 (1.5 to 4.8)	44/74	2.2 (1.1 to 4.0)
Quintile 5	23/26	2.9 (1.4 to 5.6)	56/74	2.7 (1.5 to 5.1)
Per 1 SD increase^d	182/370	1.50 (1.24 to 1.81)	182/370	1.53 (1.25 to 1.87)
P trend	182/370	< 0.001	182/370	< 0.001

IGF-1 = insulin-like growth factor 1. ^aHormones included in the score are estrone, estradiol, estrone sulfate, testosterone, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate and prolactin, then adding IGF-1 and c-peptide. ^bRR and 95% CI were adjusted for age at blood draw and menopause, parity, history of benign breast disease, family history of breast cancer, fasting status and time of day of blood draw. ^cScore is the number of hormones for which the participant had higher than the age- and assay batch-adjusted geometric mean hormone level. Among controls, the score with sex hormones and prolactin mean = 4.1 (SD = 2.4) and the score including IGF-1 and c-peptide mean = 5.0 (SD = 2.4). ^dScore is the sum of the log₂-transformed hormone level multiplied by the β coefficient for that hormone with breast cancer risk. Among controls, the score with sex hormones and prolactin mean = 10.8 (SD = 1.1) and the score including IGF-1 and c-peptide mean = 12.1 (SD = 1.2). ^eQuintile cutpoints based on hormone score including all hormones.

ISSN: 1465-542X