Table 1.

Describing the various factors and their consequences which results in risk for breast development.

Risk factors	Consequences	Ref
Early puberty	At puberty, undifferentiated, proliferative breast cells increase rapidly and more exposure to hormonal changes increases susceptibility to mutagens	[210]
Early menarche	At menarche, breast cells tend to grow and divide increasing the risk of breast cancer	[211]
Late marriage age	Prolong exposure to estrogen hormone	[212]
Late child birth age	Lack of breast tissue differentiation and prolong exposure to estrogen hormone	[213]
Lactation failure	Lack of breast tissue differentiation, more susceptible to nonestrogenic mutagens and estrogen	[214]
Late menopause age	Late onset of breast involution and prolong exposure to estrogen and progesterone	[215]
Lack of physical activity	Reduced exposure to sex hormones due to increase the number of anovulatory cycles	[216]
High fat diet	Cholesterol activate estrogen signalling and cell proliferation	[217]
Obesity	Increased levels of inflammatory cytokines and chemokines	[52]
Alcohol consumption	Increase estrogen hormone	[218]
Smoking	Induce gene mutations such as p53 gene mutation and DNA adducts	[219]
HRT	Prolong exposure to estrogen hormone	[220]
Contraceptive	Contraceptives contain progesterone and estrogen	[221]
Family history	BRCA1/2 gene mutations	[222]
Environmental toxicants	Pollutants can disrupt endocrine signalling	[223]