Breast Cancer

What causes breast cancer?

The causes of breast cancer are not exactly known but there are risk factors that increase the chance of developing breast cancer.

What are the risk factors of breast cancer?

Having risk factors do not mean a woman will definitely develop breast cancer, as many women who have had breast cancer did not have any apparent risk factors.

Some risk factors such as gender and age, or those related to our environment cannot be changed (non-modifiable), while others are modifiable as they are related to our lifestyle choices.

Non-modifiable Risk Factors

• Age and gender
• Early menarche, late menopause
• Family history and genetic factors
• Previous breast cancer
• Certain breast changes in biopsies (such as atypical ductal hyperplasia and LCIS)
• Radiation exposure for medical reasons

Being a woman is a risk factor for developing breast cancer. Women have a much higher chance of developing breast cancer than men due to the female hormones oestrogen and progesterone.

This risk is increased with longer hormonal exposure in women with early menarche (onset of menstruation) before the age of 12 and late menopause (after the age of 55).

Other hormonal-related factors include never having children, late childbearing (after the age of 30), and obesity, especially excessive weight gain in post-menopausal women. This risk also increases with age.

Genetic factors and family history of breast cancer, especially in a first-degree relative (mother, sister or daughter), or two or more close relatives such as cousins and the presence of genetic alterations in certain genes such as BRCA1 and BRCA2 which are associated with significant lifetime risks of breast cancer.

A past history of breast cancer, radiation exposure for medical reasons and certain benign conditions such as atypical ductal hyperplasia, atypical lobular hyperplasia or lobular carcinoma in-situ diagnosed on breast biopsy also increase the risk.

Modifiable Risk Factors

• Lack of exercise
  
• Excessive alcohol consumption over a long period of time
• Smoking
• Use of oral contraceptive pills (OCP) and combined hormonal replacement therapy (HRT) over a long period of time

However, most women who have breast cancer have none of the above risk factors. Likewise, not possessing any of these risk factors does not mean that one will not get breast cancer. There is ongoing research to learn more about these factors, as well as ways to prevent breast cancer.