What is Breast Cancer?

The breast is a body part with major symbolic meaning and functions. Although its primary biological role is breastfeeding infants, for some women the breast is significant in terms of aesthetics, seduction and sexuality.

Anatomy of the breast

The female breast is made up of cells and structures that produce and secrete milk.

Some definitions from the :

• Mammary glands: the cells responsible for milk production. They are made up of 1,525 small structural units, called lobules, that produce milk when stimulated by prolactin, a hormone secreted during pregnancy.
• Excretory ducts: they carry the milk from the mammary glands to the nipple.
• Nipple: the protruding end through which milk is expelled.
• Areola: the brownish or pinkish part around the nipple. It contains glands that produce secretions to lubricate and disinfect the nipple and areola. The areola also has a muscle that erects the nipple.
• Adipose tissue: it is the fatty tissue that protects the breast. The amount of adipose tissue varies from one woman to the next.
• Connective tissue: it is a structural tissue. The breast is also supported by ligaments that cross the breast from the skin to the pectoral muscle.
• Lymphatic system: it protects us from infections and diseases. It carries lymph, a fluid containing immune-system cells called lymphocytes that eliminate foreign bodies, bacteria and viruses. This system is made up of lymphatic vessels that collect and transport lymph away from the breast to small and bean-shaped masses of lymphatic cells, called lymph nodes. The lymph nodes filter foreign bodies and cancer cells out of the lymph.

Breast cancer is characterized by abnormal and uncontrollable cell growth. This cell proliferation causes tumour formation and organ dysfunction.

Cells have several mechanisms to protect themselves and prevent cancer from developing. However, cancer cells are able to transform and bypass or inactivate these mechanisms, which are summarized below:

Protection mechanisms

• Proliferation (multiplication)
• Cell division
• Tumour suppression
• DNA repair
• Apoptosis (programmed cell-death mechanism)
• Shortening of telomeres (inactive DNA fragments)
• Senescence (stopped proliferation)

Breast cancer is an issue that affects us all!

In Quebec in 2021 :

• 8,045 women were diagnosed with breast cancer, and 1,383 Quebec women died from the disease.
• Women aged 50 to 69 have the highest rate of breast cancer.
• 68 men were diagnosed with breast cancer, and 16 Quebecers died from the disease. Learn more about male breast cancer here.

These statistics indicate that if these trends continue:

• 1 in 8 women will develop breast cancer in her lifetime.
• 1 in 36 women will die of breast cancer.

Some survival statistics

• Statistics show that an early detection improves the chances of survival and access to more effective treatments.
• Mortality rates due to breast cancer have been steadily decreasing since the mid-1980s. In fact, the age-standardized mortality rate⁽¹⁾ has fallen by 40% since 1986. The five-year survival rate is currently 89% for women and 76% for men.

This reduction can be explained, among other things, by earlier diagnosis, in particular through the Québec Breast Cancer Screening Program (PQDCS). Moreover, treatments for breast cancer are getting better and better because of research programs.

⁽¹⁾ Number of cancer deaths per 100,000 resident, adjusted for the age distribution of the Canadian population in 1991, to take into account the changes in the age distribution over time.

References

• Canadian Cancer Statistics Advisory Committee in collaboration with the Canadian Cancer Society, Statistics Canada and the Public Health Agency of Canada. Canadian Cancer Statistics 2023. Toronto, ON: Canadian Cancer Society;2023. Available at: cancer.ca/Canadian-Cancer-Statistics-2023-EN (accessed august 2024).
• Canadian Cancer Statistics Dashboard. https://cancerstats.ca (accessed august 2024).
• Statistics from the Quebec Cancer Registry of the Ministère de la Santé et des Services sociaux (accessed august 2024).