Breast Cancer Health Article

Definition

Breast cancer is a disease in which abnormal breast cells begin to grow uncontrollably, forming tumors. It often shows up as a breast lump, breast thickening, or skin change.

Description

The breasts are areas of tissue located on the front chest wall, and are essentially part of the skin. They are like "specialized sweat glands" in their structure and function, in that they can produce and secrete fluids, like milk. They are made of ductal tissue, supporting connective tissue, and fat. The breasts naturally drain fluid through the lymph channels to the axillary lymph nodes, located in the armpit areas. Within the breasts are intricate structures of ducts and lobules, which are channels and areas that create and transport milk during lactation.

Excluding skin cancers, breast cancer is the most common cancer among women and the leading cause of death in women in their middle years of life. Male breast cancer, though rare, accounts for less than 1% of all breast cancers. Both genetic and environmental factors are thought to cause breast cancer. Of all breast cancer diagnoses, only approximately 5-10% are caused by hereditary factors like specific alterations in breast cancer susceptibility genes, or by a genetic cancer syndrome. In these instances, individuals may have a strong family history of cancer and the cancers may be diagnosed at an earlier age than usual.

Breast cancers vary in their type and size, and this can be determined by a breast biopsy. Breast cancer may commonly be detected by a mammogram, a physician's clinical breast examination (CBE), or a patient's own breast self-examination (BSE). Breast cancer, if it is the first cancer diagnosed, may sometimes metastasize (spread) to other organs, such as the liver, bone, lungs, skin, or brain. The breasts may also be the site of metastasis from other primary cancers.

Breast cancer may present as a lump or other change within the breast. As with other types of cancer, the initial diagnosis may be unexpected. Each cancer has a unique prognosis, and this will affect the patient's concern. If an individual has a very strong family history of breast cancer, the diagnosis may be somewhat expected, but no less emotionally taxing. Treatment and management of the cancer may be extremely exhausting, painful, and stressful for the patient and his or her family.

Genetic profile

Cells in breast tissue normally divide and grow, according to controls and instructions of various genes. If these genes have changes within them, the instructions for cellular growth and division may go awry. Abnormal, uncontrolled cell growth may occur, causing breast cancer. Therefore, all breast cancers are genetic because they all result from changes within genes. However, most breast cancers occur later in life after years of exposure to various environmental factors that can cause alterations (such as the body's own hormones, asbestos exposure, or smoking).

A small proportion of breast cancers is caused by inherited genetic alterations. In 1994 a breast cancer susceptibility gene, known as BRCA1 (location 17q21), was identified. The discovery of BRCA2 (location 13q12) followed shortly in 1995. Women with alterations in these genes have an increased risk for breast and ovarian cancer, and men have an increased risk for prostate cancer. Men with a BRCA2 alteration have an increased risk for breast cancer. Slightly increased risks for colon and pancreatic cancers (in men and women) are associated with BRCA2 alterations.

BRCA1 and BRCA2 alterations are inherited in an autosomal dominant manner; an individual has one copy of a BRCA alteration and has a 50% chance of passing it on to each of his or her children, regardless of that child's gender. Nearly all individuals with BRCA alterations have a family history of the alteration, usually a parent. In turn, they also may have a very strong family history of breast, ovarian, prostate, colon, and/or pancreatic cancers. Aside from BRCA1 and BRCA2, there likely are other breast cancer susceptibility genes that are still unknown (such as BRCA3). Additionally, there may be other genes that convey increased risks solely for other cancers, such as ovarian cancer.

BRCA1 and BRCA2 are thought to function as "tumor-suppressor genes," meaning that their normal role is to prevent tumors from forming. Specifically, they control cellular growth and division, all the while preventing the over-growth that may lead to cancer. Alterations in tumor-suppressor genes, such as BRCA1 and BRCA2, would naturally lead to an increased risk of developing cancer. However, this risk is not 100%.

There are rare, genetic cancer syndromes that may include breast cancer. As a group, these comprise less than 1% of all breast cancer diagnoses. In these instances, an individual may have other health problems (unrelated to cancer) and a family history of a wide variety of cancers and symptoms. These health problems can initially appear unrelated, but may be caused by alterations in a specific gene. As an example, Cowden syndrome typically involves early-onset thyroid and breast cancers, as well as specific tissue growths on the face, limbs, and mouth. An individual with Cowden syndrome may have all or some of these symptoms. It is now known that alterations in the PTEN gene cause Cowden syndrome. Other known cancer syndromes are caused by specific alterations in different genes. These genes are responsible for the various symptoms and cancers in an individual.