What are the causes and risk factors of breast cancer ?
The causes and risk factors for breast cancers are numerous. Approximately 10% of breast cancers are attributable to genetic mutations.
TO REMIND YOU
Genetic mutations are changes that occur in one or more genes, these small fragments of DNA that guide the functioning of cells.
Mutations can potentially be passed
from a parent to a child (hereditary genetic mutations)
or occur spontaneously during life.
Some mutations can increase the risk of developing cancers such as breast cancer.
When diagnosing breast cancer, these mutations are searched for in blood cells after a simple blood test or in cancer cells on a biopsy or surgical specimen . The discovery of certain mutations can alter cancer treatment.
Among these mutations, those affecting the breast cancer gene 1 (BRCA1) or breast cancer gene 2 (BRCA2) are particularly important as they account for 45% of cases of hereditary breast cancers.
Les mutations de ces gènes BRCA sont cependant rares dans la population générale puisqu’elles affectent environ 1 personne sur 500.
Mutations in these BRCA genes are rare in the general population as they affect approximately 1 in 500 people. They are more common in certain populations.
💡 DID YOU KNOW ?
The likelihood that breast or ovarian cancer is linked to a mutation in the BRCA1 or BRCA2 gene is higher in families where:
- Several members have had breast or ovarian cancer
- At least one relative has had breast cancer before the age of 50
- A relative has been diagnosed with both breast AND ovarian cancer
- Members have had cancer in both breasts
- A male member has had breast cancer
Studies show that women with hereditary mutations in the BRCA1 or BRCA2 gene have up to an
85 % risk
of developing breast cancer.
These women also have a higher risk of developing breast cancer at a younger age, usually before menopause. A mutation in one of the BRCA genes also increases the risk of cancer in both breasts (source: Canadian Cancer Society).
More broadly, the presence of family history of breast or ovarian cancer is a risk factor for breast cancer. This familial predisposition can be due to a hereditary genetic mutation (see above), the lifestyle of family members, chance, or a combination of these different factors.
Other risk factors are related to the presence of dense breasts, history such as early menstruation, late menopause, late pregnancy, no pregnancy, short breastfeeding, or no breastfeeding.
Chest radiation, type 2 diabetes, hormone replacement therapy, oral contraceptives, smoking, alcohol consumption, obesity, a high-fat low-fiber diet, lack of physical exercise, and age are also risk factors (source: The Lancet).
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Article updated on Sep 10, 2024
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