What Is Breast Cancer?
Cancer is the unrestricted growth of abnormal cells, which can happen virtually anywhere in the body, including the breast. Because the breast isn’t an organ that is crucial for life, cancer of the breast itself is not that dangerous, or, often, even noticeable. Rather, it’s when cancer spreads beyond the breast and lymph nodes to vital organs that the disease can become fatal.
A discussion of breast cancer often focuses less on the details of breast disease and more on the particulars of diagnosis and treatment, which are based in part on the “stage” of the disease. Staging is a scientific system of determining the extent of the disease. Along with the stage of the disease, the type of breast cancer a woman has also affected the choice of appropriate and effective therapy.
Many types of breast cancer
Cancerous (or malignant) cells in the breast develop into tumors, which can begin in the milk glands, milk ducts, fatty tissue, or connective tissue of the breast. Tumors that go undetected and untreated can spread (or metastasize) first to surrounding breast tissue, then to the lymph nodes under the arm, and finally to other parts of the body.
Breast cancer types include:
- Ductal carcinoma. Cancer of the milk ducts, which usually occurs within only one breast and accounts for almost 90% of breast cancer diagnoses.
- Intraductal carcinoma. Also called ductal carcinoma in situ, or DCIS, this is a type of breast cancer caught in a very early stage.
- Lobular carcinoma. Cancer that occurs in any of the 15 to 20 overlapping sections or lobes of the breast, happens less frequently and may appear in both breasts. The condition called lobular carcinoma in situ is not actually a form of cancer, but a type of suspicious breast change that raises a woman’s risk of developing breast cancer in the future.
Other kinds of breast cancer you may hear or read about:
- Medullary carcinoma. A form of ductal carcinoma that makes up less than 5% of all breast cancers.
- Tubular carcinoma. Another rare form of ductal carcinoma, appearing in less than 2% of all breast cancer cases.
- Inflammatory breast cancer. A special class of breast cancer that causes the breast to become red and inflamed and tends to spread quickly.
- Paget’s disease of the nipple. Another form of ductal carcinoma. Signs of Paget’s disease include eczema-like changes (dryness, flakiness) in the skin of the nipple.
Learning as much as possible about the type of cancer and recognize signs of cancer a woman has can help her and her doctor select the best possible woman breast cancer treatment. Knowledge also allows a woman with breast cancer to feel more in control of her body and her life as she handles the challenge of her illness.
Who Gets Breast Cancer & Why?
A full 99% of people who develop breast cancer are women. Most women with breast cancer range in age from 30 to 80. In fact, the majority of breast cancer cases about 80% occur in women age 50 and up.
A woman’s risk increases as she ages. At age 30, your risk of getting breast cancer is only one in 5,900. By age 40, the number rises to one in 1,200. By age 50, your odds are one in 590. And women who live to age 95 have a one in eight chance of developing the disease — a number that is often quoted out of context in the media.
Breast cancer rates are higher now than they have ever been, up from only one in 17 women in 1950. Researchers debate whether the increase represents a true increase in the prevalence of the disease, or whether improved detection techniques and a boost in public awareness means more women are diagnosed today. In either case, the good news is that death rates from breast cancer have fallen due to earlier detection and better treatment.
The bad news is that the disease remains a threat, with approximately 150,000 new cases and over 40,000 deaths annually. That said, though, heart disease kills 500,000 women per year — 12 times more than breast cancer — and is far and away a greater threat to women’s health.
Possible causes and risk factors
No one knows for certain what actually causes breast cancer. Some cases may be related to a genetic predisposition, specifically the presence of oncogenes (genes that can trigger normal cells to mutate into cancer cells — see below). But why most breast cancers appear remains a mystery.
Aside from simply being a woman, a number of factors are thought to increase your personal risk of breast cancer. If you or someone else in your family has a history of breast, colon, uterine, or ovarian cancer, or if you have ever had a breast biopsy that revealed unusual changes such as hyperplasia, you are at greater risk. If you began menstruating before age 12, or if you went through menopause after age 55; or if you’ve never given birth, or gave birth for the first time after age 30, your risk for breast cancer is higher than average. Finally, and even in the absence of any other risk factors, just being 50 years of age or older puts you in the increased-risk category.
Other factors may possibly raise breast cancer risk, although hard evidence is still forthcoming. A high dietary fat intake — getting more than 35% of your daily calories from fat — seems to be linked to an increased risk. Moderate to heavy drinking (having more than one alcoholic drink per day) also appears to raise risk, but why or how is still unknown. Lack of daily exercise, or being seriously overweight (40% or more over your ideal weight) are thought to contribute to risk as well.
Environmental factors can also affect breast cancer risk. Radiation exposure, such as multiple X-rays or radiation treatment, as well as exposure to pesticides and other environmental pollutants including cigarette smoke, may all be factors in who gets breast cancer and who doesn’t.
A few drugs may, although rarely, also contribute to the development of breast cancer. Long-term use of hormones, such as the synthetic forms of estrogen used in hormone replacement therapy (HRT) and oral contraceptives (the Pill), may slightly increase breast cancer risk.
Defective genes, particularly those referred to as BRCA1 and BRCA2, are to blame in approximately 5% to 10% of all breast cancer cases. Some women with defects in these genes may also be at higher risk for ovarian cancer.
Testing for these genes is now being done on healthy women who have a strong family history of breast cancer to gauge whether they are likely to develop the disease in the future. Gene tests can also tell a woman with breast cancer whether she is a carrier of a breast cancer gene. (See Screening article.)
Remember, however, that most women who develop breast cancer have none of these risk factors, other than the natural and unavoidable risks that come from being female and growing older. Also, many more women who do have one or more risk factors will never get breast cancer.