Breast Cancer

Mammary Cancer ยท Cancer of the Breast

The Facts

A woman's breast is made up of milk glands and milk ducts, surrounded by fatty tissue and connective supports. Uncontrolled growth of cells in any of these breast tissues can cause breast cancer.

Breast cancer is the most common cancer among women. Chances of developing breast cancer rise dramatically as women age. At age 25, the chances of getting the disease are less than 1 in 1,000; at age 50, the incidence has gone up to 1 in 63 women; and at age 75, it becomes 1 in 15.

Breast cancer is rare in men, accounting for less than 1% of all cases. Breast cancer is the second most common cause of death from cancer in women.


The body's cells reproduce themselves throughout your lifetime, as tissues wear out and their cells are replaced in a controlled manner. Breast cancer - like all cancers - occurs when that control is lost and cells begin to divide at an unusually high rate.

No single trigger or cause has been identified for breast cancer. However, certain risk factors exist, which increase a woman's chance of developing it:

  • age - it's more common in women over 50
  • family history - if a woman's mother or sister had the disease before menopause, this is occasionally associated with one of two genes linked to breast cancer
  • previous breast cancer
  • family history of ovarian cancer
  • age of pregnancy - women who haven't had children, or whose first child was born after age 30
  • age of menstruation - starting periods at a young age (under 12 years old)
  • entering menopause later (over age 55) increases breast cancer risks
  • recent research suggests that women who start smoking regularly within 5 years of the onset of their menstrual periods are 70% more likely to develop breast cancer before the age of 50 than non-smokers
  • having dense breast tissue
  • radiation treatment to the chest, especially before 30 years of age
  • alcohol consumption contributes to the risk of breast cancer
  • hormone replacement therapy (HRT; estrogen plus progesterone) increases the risk of breast cancer slightly after 5 years of therapy
  • oral contraceptives increase risks slightly, if used over many years
  • obesity with excess caloric and fat intake

The increased risks of getting breast cancer associated with the above factors are often statistically quite small. In fact, for most women, the only risk factor they have is being over 50 years of age. Any concerns should be discussed with your doctor.

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The contents of this health site are for informational purposes only. Always seek the advice of your physician or other qualified healthcare provider regarding any questions you may have about a medical condition.

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