What is breast cancer ?
Breast cancer, or more accurately "breast cancers" are malignant tumors that develop from normal cells in the mammary gland.
The term "breast cancers" is more appropriate because it has been demonstrated that there are at least four different types of breast cancer with distinct characteristics. Prognosis, progression, and management can vary depending on the type of breast cancer.
TO REMIND YOU
The biological function of the breast is to produce milk to nourish the newborn.
Each breast contains an envelope , a supporting adipose (fatty) tissue , and a mammary gland .
The gland is composed of 15 to 20 lobes separated by adipose tissue. The lobes are made up of lobules that produce milk . Galactophore ducts allow milk to flow from the lobules to the nipple.
Breast cancer cells can originate from the cells of a duct: these ductal cancers represent 85% of breast cancers . They can also originate from the cells of a lobule: these lobular cancers represent 10 to 15% of breast cancers .
The breast is traversed by blood vessels and lymphatic vessels . The latter join the lymph nodes located near the breasts in the armpit area ( axillary nodes ), above or below the collarbone, or inside the chest, around the sternum.
The mammary glands develop and function under the influence of sex hormones produced by the ovaries. These hormones are of two types: estrogen and progesterone . Estrogens notably allow for breast development during puberty. Progesterone plays a role in the differentiation of breast tissues.
Breast cancers are not new diseases, as the earliest descriptions date back to ancient Egypt, approximately 2500 years before Christ.
They are the most common cancers in women, particularly in industrialized countries. Men can also develop breast cancer, but cases are extremely rare. Therefore, this article will only focus on breast cancers in women.
In France, the number of new cases of breast cancer (incidence) was 58,500 in 2018, which accounts for one-third of female cancers (source: INCA).
Approximately one in eleven women will develop breast cancer during their lifetime (source: ARCAGY).
The incidence of these cancers has increased by 1 to 3% per year over the past 30 years.
More recently, this increase has been less pronounced (0.6% per year between 2010 and 2018). The rise in incidence of these cancers is mainly attributable to increased exposure to certain risk factors, population growth, and aging.
Breast cancer remains the leading cause of cancer-related mortality in women.
However, in recent years, mortality rates have decreased despite the increase in incidence: the mortality rate decreased by 1.3% per year between 2005 and 2018.
This decline is primarily attributed to early detection through screening, as currently 60% of breast cancers are diagnosed at the localized stage. It is also attributed to advancements in cancer treatments which are becoming increasingly effective.
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Article updated on 27 sept. 2024
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