Breast Cancer

Breast Cancer - A Look at the Pathology and Risk Factors Associated With This Common Disease
By BC Gabe

Breast tissue is composed of different types of cells. They include adipocytes (fat cells), myoepithelial cells, duct cells, and lobular cells. Breast cancer is divided into different types depending on which of the above cells it arises from.

The most common type arises from the cells that make up the milk ducts. Not surprisingly, it is referred to as "ductal carcinoma". The pre-cancerous stage is known as "ductal carcinoma in situ" (DCIS). In DCIS the duct cells have features of cancer, but they have not yet "broken" through the tissue layer that separates the duct cells from the other tissue types of the breast. Once the cells become malignant enough they can invade through the basement membrane; at this point it is considered cancer.

Cancer can also arise from the lobular units of the breast. When this occurs it is referred to as "lobular carcinoma". It is a less common form of carcinoma making up roughly 10% of all cases. An even rarer form is referred to as inflammatory carcinoma; it accounts for less than 1% of cases.

Hereditary breast cancer is the exception rather than the rule. It is usually caused by mutations in either the BRCA-1 or BRCA-2 genes. The protein products of these genes normally function as "tumor suppressors" via the prevention of abnormal replication of cells. However, when these genes become mutated they are no longer able to suppress abnormal replication and cancer can develop.

The known risk factors for the development of breast cancer include: mutations in BRCA-1 or 2, nulliparity, first pregnancy at age 35 or older, menstruation beginning before age 13, menopause occurring after age 55, history of cancer, female sex (males can develop breast cancer too!), age greater than 65, and two or more first degree relatives with breast cancer.

If a breast biopsy is done that shows any of the following under the microscope, the risk of subsequently developing breast cancer is also increased: papilloma of the breast, ductal carcinoma in situ, lobular carcinoma in situ, sclerosing adenosis, and atypical hyperplasia.

Interestingly, 70 to 75% of women have no known risk factors for developing breast cancer.

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