Table 1.

Lifelong changes in the levels of sex hormones and insulin resistance in women and their correlations with overall and TN breast cancer risk

Hormonal changes in the life periods of women	Estrogen level	Androgen level	Insulin resistance	Overall and TNa breast cancer risk		References
Adolescence
Menstrual disorder	↓	↑	↑	↑↑	↑	33
Anovulatory cycles	↓	↑	↑	↑↑	↑	33
Phytoestrogen use	↑	↓	↓	↓↓	↓	134
Premenopausal women
Anovulatory infertility	↓	↑	↑	↑↑	↑	33,145
Nulliparity	↓	↑	↑	↑↑	↑	155,156
PCOS	↓	↑	↑	↑↑	↑	69
Contraceptive use	↑	↓	↓	↓↓	↓	50,51
Parity	↑	↓	↓	↓↓	↓	139,144
In vitro fertilization	↑	↓	↓	↓↓	↓	145
High-dose estrogen	↑	↓	↓	↓↓	↓	157
Postmenopausal women
HRT use	↑	↓	↓	↓↓	↓	55,76
Non-HRT use	↓	↑	↑	↑↑	↑	33,55
Hysterectomy	↓	↑	↑	↑↑	↑	55

Notes:

^aChanges in overall and TN breast cancer risk exhibit similar trends under hormonal alterations; however, the extent of this change is lower among TN tumors, due to the lack of estrogen receptors. Reprinted with permission from Bentham Science Publisher. Copyright © 2013. Suba Z. Circulatory estrogen level protects against breast cancer in obese women. Recent Pat Anticancer Drug Discov. 2013;8(2):154–167.³³

Abbreviations: HRT, hormone replacement therapy; PCOS, polycystic ovarian syndrome; TN, triple-negative.