Why is Early Detection Important?

Women who had breast cancer in the past have a higher risk of developing breast cancer again.

A family history of breast cancer means that one or more close blood relatives have or had breast cancer. Some families have more cases of breast cancer than would be expected by chance. Sometimes it is not clear whether the family’s pattern of cancer is due to chance, shared lifestyle factors, genes passed from parents to children or a combination of these factors.

The risk of developing breast cancer is higher if:

• one or more first-degree relatives (such as a mother, sister or daughter) had breast cancer, especially if they were diagnosed before menopause;
• second-degree relatives (such as a grandmother, aunt or niece) from either the mother’s or the father’s side of the family had breast cancer;
• a relative had cancer in both breasts (called bilateral breast cancer) before menopause;
• 2 or more relatives had breast cancer or ovarian cancer;
• a relative had both breast cancer and ovarian cancer;
• a male relative had breast cancer.

Having one first-degree relative with breast cancer approximately doubles a woman’s risk. The more first-degree relatives with breast cancer, the greater the risk. The risk with second-degree relatives is not as much as the risk with first-degree relatives.

Genetic mutations are changes to a gene. Some gene changes can increase the risk of developing certain types of cancer. Inherited gene mutations are passed on from a parent to a child. Only a small number of breast cancers (about 5%–10%) are caused by an inherited gene mutation.

The likelihood that breast or ovarian cancer is linked with an inherited BRCA1 or BRCA2 mutation is highest in families that have:

• a history of family members with breast or ovarian cancer;
• breast cancer that developed before age 50 in 1 or more female relatives;
• a single relative diagnosed with both breast and ovarian cancer;
• family members who develop cancer in both breasts;
• a male relative diagnosed with breast cancer.

Dense breasts have more connective tissue, glands and milk ducts than fatty tissue. Breast density is an inherited trait. Women with dense breast tissue have a higher risk of developing breast cancer than women with little or no dense breast tissue.

Breast density can only be seen on a mammogram, but dense breasts also make a mammogram harder to read. On a mammogram, fatty tissue looks dark, while dense tissue looks white, like tumours, so it can hide a tumour.

• Drinking alcohol increases a woman’s risk for breast cancer. Even low levels of alcohol consumption (just over 1 drink per day) can increase a woman’s risk. The risk increases with the amount of alcohol consumed;
• Not maintaining a healthy body weight;
• Physical in-activity.

Visit the Canadian Cancer Society to learn more about other risk factors that may contribute to a breast cancer diagnosis.