Risk factors

Are you at risk for breast cancer?

If you answered yes, you’re not alone. If you answered no, think again.

The most proven and significant breast cancer risk factors are being female and getting older. In other words, all women are at risk for breast cancer, with the greatest risk occurring after the age of 55. But there are several other known risk factors – some of them are related to your body (endogenous) and some are related to lifetime exposures, environmental changes and medicines (exogenous).

Having several risk factors doesn’t mean you will get breast cancer. It just means that your chances of getting the disease are higher than those who have fewer risk factors.

Hormonal factors

Some of the major breast cancer risk factors are hormonal and related to a woman’s reproductive history. The greatest risk results from breast tissue being consistently exposed to estrogen, as it is through long periods of uninterrupted menstrual or ovulatory cycles.

Hormonal factors that increase risk include:

  • the birth of a first child after the age of 30 or not having children at all
  • menstruation starting at an early age (before 12)
  • late menopause (after 55)
  • taking birth control pills and /or hormone replacement therapy (although debated, many experts say that this slightly increases one’s risk)

Genetic factors

Over the past decade, two breast cancer susceptibility genes have been discovered and characterized: BRCA-1 and BRCA-2. Certain inherited mutations (changes) in either of these genes will increase a woman’s risk of developing breast cancer. Still, those with a well-documented genetic predisposition to breast cancer only account for 5%-10% of cases diagnosed. These women have a higher risk of developing breast cancer at a younger age (before menopause) and they often have multiple family members with the disease.

Did you know?

A woman’s risk is up to 10 times greater if her mother or sister has had breast cancer in both breasts, and six times greater if her mother or sister had breast cancer before menopause.

Environmental factors

Evidence shows that your country of origin, where you live and what you’re exposed to throughout your life can impact your risk of developing breast cancer.

Did you know?

  • The occurrence of breast cancer varies about five-fold among countries.
  • Canada and the U.S. are considered high-risk countries, while Japan and China are low risk.
  • Migrants eventually acquire the risk of their adopted country.
  • Being exposed to high levels of radiation, especially to the chest (through, for example, frequent X-rays in youth), increases your risk.

Lifestyle factors

Evidence shows that lifestyle factors that increase estrogen levels increase your risk of developing breast cancer.

Lifestyle factors that increase risk include:

  • more than mild or moderate alcohol consumption (alcohol may raise estrogen in the blood)
  • obesity with excess caloric and fat intake (fatty tissue may raise estrogen levels)
  • more than moderate meat intake (meat may raise estrogen levels and be a potential source of gene mutagens). Studies have shown an 18% difference in risk of breast cancer between those with the highest and those with the lowest levels of meat intake.

Personal history

You have higher risk of developing breast cancer if:

  • You have a personal history of breast or ovarian cancer.
  • You had a previous biopsy showing abnormal cells.
  • You have high bone density.
  • You’re shown to have high breast density on a mammogram.
Quick fact

Only 5%-10% of all breast cancers happen because of inherited genetic mutations.

Titbit

Knowing your risk factors is the first step toward reducing your risk.