Risk factors for breast cancer


Research has shown an ever-expanding list of major, minor, and suspected risk factors. The major risk factors are largely related to age and genetics, while the minor risk factors come from reproductive status and lifestyle issues,so it is quite useful to join the Breast Cancer Support Groups. The suspected risk factors have some correlation to breast cancer in limited studies, but further research is warranted. Risk factors are cumulative: the more factors present, the higher the relative risk.


Advancing age is the most influential risk factor for developing breast carcinoma. About 77% of breast cancers occur in women older than 50 years of age reported by health qas web. Incidence increases exponentially during the postmenopausal period, reaching its peak in the eight decade.

A woman with a previous history of breast cancer is at an increased risk for subsequent breast cancer. The risk of developing a second primary breast cancer is approximately 0.7% per year after the diagnosis of the initial breast cancer. Subsequent breast cancer rates are higher in woman whose initial tumor was lobular in situ and occurred premenopausally.

Approximately 15% to 25% of all breast cancers occur in women with a positive family history of breast cancer in a first-degree relative (mother, sister, or daughter). If the first-degree relative’s breast cancer occurred before the age of 50 and was bilateral, the lifetime cumulative risk appears to be greater than 50%.


Both early menarche (<+11 years) and late menopause (>=55 years) are associated with an increased risk of breast cancer. For each 5 years change in menopausal age, the risk of breast cancer changes by approximately 17%. Women who reach menopause before age 45 years have one half the breast cancer risk of those who reach menopause after age 55 years.

Nulliparous women have a higher likelihood of developing breast cancer than their parous counterparts. Women who carry their first pregnancy to term after 30th birthday have twice the breast cancer risk of women who have their first child before age 20. it is estimated that women who first give birth after age 35 years have three times the breast cancer risk of those who had a full-term gestation before the age of 30.


A relation between high dietary fat intake during midlife and increased rates of breast cancer has long been suspected, primarily because of international variations in breast cancer incidence, but no causal association has yet been demonstrated. And while the relationship between breast cancer and dietary fat intake during childhood and adolescence has not been evaluated, it has been suggested that a marked reduction in dietary fat at any age may have a protective effect against developing breast cancer.

Heavy body weight has been shown to result in an increased risk for developing cancer of the breast in postmenopausal women and a decreased risk in pre-menopausal. The liability of obesity may be related to estrogen metabolism; increased adipose tissue makes available an increased amount of androstanedione for conversion to estrogen.

Literature indicates that a personal history of atypical hyperplasia and family history of breast cancer combined with exogenous estrogen exact a modestly increased risk for malignant breast cancer.

While studies have shown a positive correlation between alcohol use and breast cancer, the association has been weak.

Women who smoke cigarettes may incur a higher risk for developing breast cancer compared with their nonsmoking counterparts. The carcinogenic nature of cigarette smoking has been well documented and further evaluation of its particular relation to breast cancer is probably not warranted.

A number of toxic environmental agents, particulary pesticides, have been linked to the development of breast neoplasia in women, although the evidence is inconclusive. The estrogenic nature of some pesticides are now being researched.