Various epidemiological studies have indicated a number of genetic and environmental factors that can predispose breast cancer.
Following is a list of such Breast cancer risk factors:
- Age: Older age women are generally at increased risk of developing breast cancer. About 70% of all the incidences of breast cancer are observed in women older than 55 years of age.
- Early menarche/late menopause: Commencement of menstrual cycles (menarche) at an early age or cessation of menstrual cycles (menopause) at a later age than normal have been reported to elevate the risk of developing breast cancer. The increased risk is postulated to be related to the longer duration of exposure to female sex hormones, estrogen, and progesterone.
- Delayed marriage or childbirth: It has been reported that women who get married and have children by the age of 26 years are generally at lower risk of developing breast cancer. While women who got married at a later age and have pregnancy after 35 years of age or who never have had a full-term pregnancy are at increased risk of developing breast cancer.
- Females with a personal history of breast cancer or a benign breast disease, for example (e.g.), papilloma, atypical hyperplasia, or lobular carcinoma in situ are generally at higher risk of developing breast cancer.
- Family history: Individual with a history of breast, ovary and certain other cancers in close relatives are considered to be at increased risk of developing breast cancer.
- Genetic alterations: Many inherited genetic alterations have been reported to be associated with a high incidence rate of breast cancer, for example (e.g.), a mutation in the following genes have been reported to increase the risk of breast cancer: BRCA1,BRCA2, ATM, TP53, ERBB2, CHEK2, PTEN, CDH1, STK11, PALB2 and many other.
- Dense Breast: It has been observed that females with dense breast tissue (less fatty tissue and more glandular and fibrous tissue) are at about 1.5 to 2 times higher risk of developing breast cancer compared to females with normal breast tissue.
- Prolonged hormonal replacement therapy: Women who are using or who have used hormone replacement therapy (HRT) after menopause for many years are generally at higher risk of developing breast cancer.
- History of Radiation therapy to Breast or Chest: Women with a history of radiation treatment to their breast or chest, especially at a younger age, are at increased risk of developing breast cancer.
- Obesity: Overweight or obese females are at higher risk of developing breast cancer which may be due to the higher exposure to estrogen produced in the fat tissue after menopause.
- Alcohol: Excessive alcohol consumption has been reported to increase the risk of breast cancer and the risk increases with the increase in the amount of alcohol consumed.
- Diet: It has been reported that a diet rich in red meat, processed meat, and fats, may increase the risk of breast cancer, while an adequate consumption of vegetables and fruits may reduce the risk of breast cancer.
Limited physical activity and prolonged use of oral contraceptives have also been linked to increased incidence of breast cancer.