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Breast Cancer: Several Possible Causes

In spite of scientific and medical advancements, the causes of breast cancer remain unknown. According to experts, there is no single cause or no single factor that triggers breast cancer. Scientific studies show that several factors contribute to the risk of breast cancer.

One of the major risk factors is the effect of certain female hormones, estrogen in particular, that favour the development of certain types of breast cancer. Consequently, all elements that are likely to increase the level of estrogen in the body, or to increase the length of exposure to this hormone, constitute a risk factor.

The presence of higher estrogen levels or the prolonged exposure to it is caused mainly by early menstruation, taking oral contraceptives, first pregnancy at a later age or absence of pregnancy, not breastfeeding, late menopause, prolonged hormonotherapy to treat the symptoms of menopause, obesity and consumption of alcohol. 

While some risk factors are non-modifiable, which means they are beyond our control, others, such as obesity, taking oral contraceptives, and the consumption of alcohol, are modifiable as they are related to lifestyle choices. The modifiable risk factors are an indication of the fact that breast cancer is more common in industrialized countries like Canada, the U.S., northern Europe and Australia. The breast cancer incidence in Canada is among the highest in the world.

Finally, the risk of developing breast cancer increases for women with one or more family members who have had the disease. However, the majority of women diagnosed with breast cancer do not have a family history of it.