Obesity as potential breast cancer risk factor for postmenopausal women

Abstract

Breast cancer is the second highest prevalent cancer globally after lung cancer with 2.09 million cases during 2018. Adults about 1.9 billion were overweight and over 650 million out of these were obese during 2016. There is a significant relationship between breast cancer risk and obesity. Premature menopause and premenopausal obesity diminish the risk whereas postmenopausal obesity amplifies the risk, because adipose tissue acts as the major reservoir for estrogen biosynthesis after menopause. Lofty estrogen levels in serum along with enhanced peripheral site production of estrogen have been viewed as major reasons of developing breast cancer in overweight postmenopausal women. This review explains body fat as a peripheral site for estrogen biosynthesis, estrogen exposure affecting body fat distribution, and the mechanism of estrogen production from body fats.

Keywords: Adipocyte; Aromatase; BMI, body mass index; Breast cancer; E2, estradiol; ER, estrogen receptor; Estrogen; GPER1, G protein-coupled estrogen receptor 1; GPR30, G protein-coupled receptor 30; IL-6, interleukin-6; IRS-1, insulin receptor substrate-1; MAPK, mitogen-activated protein kinases; Obesity; TNFα, tumor necrosis factor-α.

Figure 1

Fat distribution pattern in male and female.

Figure 2

Sites of estrogen synthesis in premenopausal and postmenopausal females.

Figure 3

Biosynthesis of estrogen.