Risk Factors

Every woman wants to know how they can eliminate the risk of having breast cancer, but even the healthiest men and women could be affected. Unchangeable factors such as gender, genetics and your age are directly associated with breast cancer. Living a healthy lifestyle by maintaining a healthy weight, eating nutritional foods and exercising, and avoiding unhealthy lifestyle choices such as smoking cigarettes and drinking alcohol, can lower the chances of having breast cancer (via the Canadian Cancer Society and Cancer Care Nova Scotia).

Who is considered “High Risk”? (via High Risk Breast Cancer Project)

“High Risk” includes women that meet one or more of the following criteria:

  • Have undergone genetic testing that confirms a mutation which increases the risk for breast cancer
  • Have a parent, sibling or child with genetic testing confirming a mutation that increases the risk for breast cancer
  • Have a family history that indicates a hereditary breast cancer syndrome and a 25 per cent or greater lifetime risk of breast cancer confirmed through a genetic assessment
  • Have a five-year risk of breast cancer of 1.7 per cent or greater at age 35 or older
  • Have a history of radiation treatment to the breast
  • Have a previous diagnosis of breast cancer
  • Have a history of lobular carcinoma in situ
  • Have very dense breasts identified by mammography

What is the difference between relative risk and absolute risk?

We often hear news reports that something has been found to reduce the risk of breast cancer, or reduce the risk of dying from breast cancer. These reports are often misleading because they use numbers representing relative risk reductions. Absolute risk reduction is what really matters, which is often much lower, and often not reported. What is the difference? (via Breast Cancer Deadline 2020)

Relative risk: is the number that tells you how much something you do, such as maintaining a healthy weight, can change your risk compared to your risk if you’re very overweight. Relative risk can be expressed as a percentage increase. If something you do or take doesn’t change your risk, then the relative risk reduction is 0 per cent (no difference). If something you do or take lowers your risk by 30 per cent compared to someone who doesn’t take the same step, then that action reduces your relative risk by 30 per cent. If something you do triples your risk, then your relative risk increases 300 per cent (via breast-cancer.ca).

Absolute risk: is the size of your own risk. Absolute risk reduction is the number of percentage points your own risk goes down if you do something protective, such as stop drinking alcohol. The size of your absolute risk reduction depends on what your risk is to begin with. Your absolute risk also depends to a great extent on your age (via Dr. Susan Love Research Foundation).

The following is an overview of established risk factors for breast cancer (via breastcancer.org):

  • Being a woman. Just being a woman increases the risk for breast cancer. There were an estimated 25,000 new cases of breast cancer in Canadian women in 2015 (Canadian Cancer Statistics 2015). Women are more likely to develop breast cancer because their breast cells are exposed to the female hormones estrogen and progesterone, which are linked with breast cancer and encourage the growth of breast cancers – especially estrogen (via cancer.ca)
  • Age. Your risk of having breast cancer increases as you age. Most breast cancer is detected in women over 50. The risk of developing breast cancer is as follows (via Willow Breast and Hereditary Cancer Support*):
    • By age 25 – less than 1 in 1,000
    • By age 50 – 1 in 63
    • By age 75 – 1 in 15
    • By age 90 – 1 in 9
  • Family history. A family history of breast cancer in the past three generations increases your risk. Having one first-degree relative with breast cancer approximately doubles a women’s risk of having breast cancer. The more first-degree relatives with breast cancer, the greater the risk; but still, most people diagnosed with breast cancer have no family history of the disease (via the Canadian Cancer Society).
  • Genetics. About five per cent of breast cancers are thought to be correlated to family genetics and BRCA1 and 2 mutations* (*this needs to be linked to the genetics section for a deeper explanation). BRCA1 and 2 are tumour suppressor genes, which normally prevent cancer from developing. Hundreds of BRCA genes mutations have been identified by researchers, and many of these are linked to an increased chance of developing breast cancer.

Dr. Akbari, an assistant professor with the Dalla Lana School of Public Health at the University of Toronto, has recently led a study at the Women’s College Hospital which identified a newly discovered gene mutation that can be associated to breast cancer. For the very first time, the study identified a strong association between mutations in a gene called RECQL are strongly linked to the onset of breast cancer in two populations of Polish and French-Canadian women.

  • Personal history with breast cancer. Previously having some types of cancer as a child or an adult can lead to a moderate-to-high increase in the risk of having breast cancer. If you have a personal history of breast cancer, you’re likely to develop a new cancer in the same breast or in the opposite breast. The risk of cancer returned is dependent on several factors: the size, type, and grade of the original cancer; its receptor status; if any lymph nodes* were affected and how many; how it responded to treatment; and the time since diagnosis. Studies suggest that women who have went through chemotherapy or hormone therapy in addition to breast cancer surgery, 11 per cent will have a recurrence within five years and 20 per cent will have a recurrence within ten years after treatment for the original cancer ends (via Canadian Breast Cancer Foundation).
  • Radiation exposure. If you’ve received radiation treatment to the chest or face before the age of 30 to treat other types of cancer, Hodgkin’s disease or non-Hodgkin’s lymphoma, or acne radiation treatment to the face as an adolescent, your risk of having breast cancer increases (via the Canadian Cancer Society).
    Certain breast changes. Most non-cancerous or benign breast conditions do not increase a woman’s risk of developing breast cancer. However, there may be a relationship between non-cancerous breast conditions and a family history of breast cancer. If you are diagnosed with a benign tumour on your breast, you may be at risk of breast cancer. Non-cancerous breast conditions that may increase the risk of breast cancer include (via Canadian Cancer Society):

    • Fibrocystic breast changes
    • Hyperplasia
    • Complex fibroadenoma
    • Sclerosing adenosis
    • Papillomatosis
    • Radial scar
  • Race/Ethnicity. Certain races and ethnicities are slightly more likely to have breast cancer as a result of family genetics (via WebMD.com). The rates of women who die of cancer vary in amongst racial and ethical groups due to hereditary genes.
  • Lack of exercise and being overweight. Especially after menopause, women who are obese or overweight in comparison to women who are a healthy weight are more likely to have breast cancer. Research shows that being overweight and lack of exercise can increase your risk of having breast cancer in comparison to men and women who live a healthy and active lifestyle. (via Sunnybrook Health Sciences Centre)
  • Pregnancy history. Women who haven’t experienced a full-term pregnancy or women who are pregnant after the age of 30 are more likely to have breast cancer in comparison to women who gave birth before the age of 30. Breast feeding can also lower the chance of having breast cancer, especially if a women’s breast feeding last longer than a year (via Canadian Cancer Society).
  • Menstrual history. Women who started menstruating before the age of 12 or menopausal after the age of 55 experience a higher risk of having breast cancer.
  • Using Hormone Replacement Therapy (HRT). Current, recent or past users of HRT increase their risk of breast cancer. Since the study of HRT breast cancer related risks in 2002, the use of HRT has dramatically declined (via WebMD.com)
  • Drinking alcohol. Research consistently shows drinking alcohol increases your risk of breast cancer. “Drinking even one alcoholic drink a day can raise the risk for breast cancer by 1.5 times. The risk of breast cancer may increase with every additional drink a woman has each day,” claims the Canadian Cancer Society.
  • Smoking. Along with dozens of other health risks associated with smoking, smoking and heavy second-hand smoking are also linked to a higher risk of breast cancer in premenopausal women (“Smoking and Breast Cancer – What’s the Link?”)
  • Having dense breasts. Research has shown that having dense breast can make you six times more likely having breast cancer. Having dense breasts also affects the clarity of mammogram screenings (What is Dense Breast Tissue?).

Breast Cancer in Young Women

Facts and Statistics (Canadian Cancer Society, Canadian Cancer Statistics 2015)

In Canada…

  • Less than 1 per cent of new breast cancer cases will occur in children and youth aged 0–19 years
  • Females have higher rates of cancer than males between the ages of 20 and 59, primarily due to breast and thyroid cancer
  • In 2015, 4,475 new breast cancer cases are estimated to occur in women under the age of 50 (accounts for 32 per cent of all cancer incidences in women in this age group)
  • Breast cancer is the leading cause of cancer deaths in women under the age of 40.
  • 18 per cent of breast cancer cases occur in women under the age of 50

A Different Challenge

Although the chance adolescents and young women will have breast cancer is significantly lower in comparison to women over 50, their breast tissue is generally denser, which makes it more challenging to detect with traditional screening. No effective breast screening tool yet exists for women under 40.

Breast cancer in adolescents and young women differs biologically in comparison to women over 40. Because detection in younger women is generally later, the cancer becomes significantly more advanced and is less likely to respond to treatment (via Canadian Breast Cancer Foundation). Since breast cancer occurs at a much lower rate among young women than in our older counterparts, they remain underrepresented in many research studies.

Women under 40 with breast cancer struggle with several unique challenges either not present or much less severe in the lives of older women. These include (via Canadian Breast Cancer Foundation):

  • The possibility of early menopause. Surgery to remove ovaries, chemotherapy and hormonal therapy — may cause your menstrual periods to stop a while or permanently (click here for more information on treatment induced menopause)
  • Effects on fertility. Because some cancer treatments can cause early menopause in some women, this sometimes leads to infertility. Your periods may start again at some point after chemotherapy or hormonal therapy. Research hasn’t yet shown a good way to predict if you will regain your periods or not, although age is a factor.
  • Questions about pregnancy after diagnosis. Before having cancer treatments, it’s important to have a discussion with your doctor about treatment options if you’re planning on getting pregnant in the future and whether or not it’s safe to be pregnant following your cancer diagnosis and treatment (Click here to learn more).
  • Challenges to financial stability. Women under 40 are often less financially stable than women over 40. Cancer is expensive and it is challenging to pay for living and treatment expenses when you do not have an income during cancer care.

Screening for Women under 50

Only British Columbia, Alberta and Nova Scotia currently provide automatic screening for women in their 40s who have not been designated as high risk. Discouraging screening on the basis that it may take several attempts to detect a cancer does a major disservice for women for whom cancer is by far the leading cause of death. In fact, young women also experience more aggressive forms of breast cancer than those who are older in age. It is important to consider your family history involving breast cancer and to consult your doctor for a risk assessment, as well as a discussion of risk management options.

More Resources for Breast Cancer in Young Women

Sunnybrook Health Services Centres PYNK is the first program of its kind in Canada to address the special clinical, psychological, research and educational needs of younger women with breast cancer.

Support for Young Families A resource for young families with breast cancer. Whether you want to speak with another young mom, find resources to help you talk to your kids about breast cancer, or get professional help with a specific concern, the group can help you and your family cope with this life-changing experience.

Rethink Young Women’s Network (RYWN) RYWN is a group comprised of women across the country that have personal experience with breast cancer and are interested in Rethink’s unique role within the breast cancer community.