63% of Albertan women aged 50-74 had a screening mammogram during 2015-2016.

Could you be at risk for breast cancer?

Sex and age are the two biggest risk factors for breast cancer. Your chances of developing breast cancer vary according to a number of other factors as well.

Breast cancer risk factors you can’t change

1 in 8 women in Alberta will be diagnosed with breast cancer in her lifetime. While there are some things you can do to reduce your risk, there are others that are beyond your control including:

  • Sex – Women are about 100 times more likely to develop breast cancer than men.
  • Age – The older a woman gets, the greater her chance of developing breast cancer. More than 3 out of 4 women diagnosed with breast cancer in Alberta are 50 years or older.
  • Family history – 80% of women who develop breast cancer have no family history of the disease, however having a mother, sister or daughter with breast cancer increases your risk.
  • Genetic changes – Specific changes to certain genes (BRCA1, BRCA2 and others) can increase a woman’s risk of breast cancer. These are rare and make up less than 10% of all breast cancer.
  • Previous diagnosis of breast cancer – Women who have had cancer in one breast are at increased risk of developing a new breast cancer.
  • Breast density – Women with denser breast tissue have a higher risk of breast cancer. Dense breast tissue also makes it harder to find breast cancer early on a mammogram. Please see the section below called ‘Breast density’ for more information
  • Menstrual history – Women who had their first period before age 12 and/or went through menopause after age 55 have a higher risk of breast cancer.
  • Radiation therapy to the chest – Women who were treated by radiation to the chest for another type of cancer are at increased risk. The younger a woman was when she had her treatment, the higher her risk of breast cancer later in life.

Breast cancer prevention – what you can do

Fortunately, many of the lifestyle choices you make can reduce your risk for breast cancer.

  • Physical Activity – Be physically active throughout your life and exercise every day.
  • Weight – Try to reach or stay at a healthy body weight. This becomes even more important after menopause.
  • Alcohol – Limit the amount of alcohol you drink to no more than one drink per day.
  • Smoking – Don’t smoke and avoid second-hand smoke. If you’re currently a smoker, talk to your healthcare provider about options for quitting or cutting back..
  • Oral Contraceptives – Taking the birth control pill may slightly increase your risk of developing breast cancer, but the good news is that the risk is small and tends to return to normal after you’ve stopped taking it for 10 years or more.  Most women taking hormonal birth control are younger and at an age when breast cancer is rare.  For women who have had a past breast cancer, hormones in the pill might have an effect on the cancer.  If you’re worried about your risk of breast cancer, you can consider switching to a non-hormonal form of birth control.
  • Long-Term Hormone Replacement Therapies (HRT) – Limit using the combination of estrogen and progestin menopausal hormone replacement therapy to no more than 5 years; long-term use (beyond 5 years) increases a woman’s risk of breast cancer. But within 2 years of stopping, a woman’s risk of breast cancer returns to average.
  • It may be helpful to know that having children before the age of 30 reduces your risk of breast cancer. Breastfeeding also lowers breast cancer risk.

Try the risk assessment tool to learn more about your breast cancer risk factors and how they may affect you.

Visit HealthierTogether.ca to learn more about ways to reduce your breast cancer risk.

Breast density

What is Breast Density?

The breast is made of fat and tissue such as milk ducts, lobules or glandular tissue and fibrous connective tissue. Breast density is the amount of fibrous or glandular tissue compared to the amount of fat in the breast.


Dense tissue shows up as white on a mammogram, the same colour as many kinds of breast cancer. For that reason, it can be harder to find cancer when you have dense breasts.

There are 4 categories of density, ranging from entirely fatty to extremely dense. The radiologist at your mammography clinic uses your mammogram to measure your density and decide on the category.


It’s very common to have dense breast tissue. Almost half of women aged 50-74 have breasts that are considered dense. There are many things that may affect your breast density including genetics, hormone levels and overall body fat. Breast density can change and also tends to go down as you age.

How Do I Know If My Breasts Are Dense?

You can’t tell how dense your breasts are by size, look or feel. The only way to find out is by having a mammogram. Some reports at your radiology clinic may mention breast density. If you aren’t sure, you can ask about your density at your mammography appointment or talk to your healthcare provider.

Dense Breasts and Cancer Risk

For women in Alberta, the risk of developing breast cancer in your lifetime is 1 in 8.

Research to date shows that women with dense breasts are diagnosed with breast cancer about 1-2 times more often than average. However, keep in mind that other factors, such as age and genetics, have a bigger impact on your overall risk of breast cancer.

Note: You might find different numbers used elsewhere. There are a few reasons for this:

  1. Numbers differ slightly depending on the study.
  2. Often the difference in risk is shown by comparing the risk for women with the greatest breast density to those with the least. This does not represent most women with dense breasts and does not tell you how that risk compares to the average.* (see our booklet ‘Breast Density and Screening’ for more information about breast density categories)
  3. Breast density changes over time and it is unclear how it impacts lifetime risk.


Tools for assessing your personal risk

Tools for Assessing Your Personal Risk

Here are some links to online resources or tools that can help you assess your risk of developing breast cancer. Each tool uses different ways to figure out your risks so your results might change from one tool to another.

Links are included by clicking on the risk assessment tool.

Title of Risk Assessment Tool Risk Assessment Tool Breast Cancer Risk Assessment Tool What’s my Risk? Assess your Risk Breast Cancer Screening Decision Aid
What  the tool is good for Can help you list the factors that raise or lower your risk of breast, cervical, and colorectal cancers. Can tell you your risk of developing breast cancer  in the next 5 years or in your lifetime. Can tell you your lifetime risk of developing breast cancer in comparison to the average risk. Can tell you your risk level for breast or ovarian cancer over your lifetime:  below average, average, increased, or high risk. Offers other helpful suggestions, such as steps you can take to lower your risk.

Can let you know your likelihood of having breast cancer found, a false alarm, or a biopsy false alarm.

Gives an idea of the benefits and limitations of screening.



(AHS resource)

National Cancer Institute

(Gail Model)

Cancer Care Ontario Brightpink BC Cancer Agency
Factors Included
Family history
Cancer history
Ashkenazi (Jewish) heritage X X X
Genetics (BRCA 1/2, etc.) X
Births given X
Breast Density X X X X
Lifestyle (alcohol consumption, physical activity, etc.) X X
Screening history X X X
Previous chest radiation treatment X X
Previous biopsy X X X
Breast cancer medication use (such as tamoxifen) X X X X
Hormone replacement X X
5 year risk X X X X
10 year risk X X X X X
Lifetime risk X X
Compared to average? X
Likelihood of a false positive from screening  X X X X
Provides health advice? X X
Lists which factors increase/decrease risk? X X
Estimated time to complete 10 min 5 min 5 min 5 min 2 min


*These resources are a guide only.

Remember, having a high risk of developing cancer doesn’t mean you will get cancer. Having a low risk also doesn’t mean you can’t get cancer.


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