Overview Breast cancer is the most common malignancy in women, except for non-melanoma skin cancers. It continues to be a major health care problem in the US and worldwide. The lifetime risk of a US woman developing breast cancer is 1 in 8 and the risk increases with advancing age: between 2002 and 2006, about 1.9% of breast cancer diagnoses were in people age 20 to 34, 10.5% were between 35 and 44; 22.5% were between 45 and 54; 23.7% were between 55 and 64; 19.6% were between 65 and 74; 16.2% were between 75 and 84; and 5.5% were 85 years or older. Over 85% of breast cancer diagnoses occurred in those age 45 and above (NCI SEER Cancer Statistics Review, 1975-2006).
After increasing continuously for more than two decades, female breast cancer incidence rates have decreased by 2.2% per year from 1999-2005.
According to the American Cancer Society (ACS), in 2009 an estimated 192,370 women will be newly diagnosed with cases of invasive breast cancer, and although uncommon, men can develop breast cancer and about 1,910 men will also be newly diagnosed. Approximately 40,610 breast cancer deaths are expected in the U.S. in 2009; among these about 40,170 women and 440 men will die from the disease.
According to ACS 2009 data, mortality rates have been declining since 1990; by 3.2% per year in those under age 50 and by 2.0% in those age 50 and older. These decreases are most likely the results of earlier detection (mammography) and improved treatment.
Tumor Types Most breast cancers fall into one of two major categories:
Lobular carcinoma: Lobular carcinoma, which occurs far less frequently than ductal, originates in glandular tissue or breast lobules.
Ductal carcinoma: Ductal carcinoma, of which there are multiple subtypes, develops in the milk ducts of breast tissue.
Carcinoma is the medical term for cancer that arises in organ tissue, such as lung, breast, colon, and so on. Cancer that affects the nipple is called Paget’s disease.
To understand the different types of breast cancer, it helps to understand the basic structure of the breast.
Lobular Carcinoma Malformed cells in glandular tissue (milk producing tissue) of the breast eventually may become a lobular carcinoma. Lobular carcinoma occurs in both an invasive and a noninvasive form. At a very early stage the noninvasive form is called "lobular carcinoma in situ" (LCIS) or "lobular neoplasia". LCIS is characterized by clusters of malignant cells that are contained within the lobule of the breast. LCIS is more difficult to diagnose than DCIS because it does not develop a mass or tumor that can be felt and does not show up on mammography. It is usually found when a breast biopsy is done for another reason.
LCIS affects only women and with a peak incidence at age 45 years, and decreasing in incidence after menopause. Approximately 90 percent of women with LCIS are premenopausal. Estrogen receptors are found in most lesions; therefore, the development of LCIS may be related to hormonal influences.
Many experts do not consider LCIS to be a true malignancy, cancer, or even a pre-malignant condition, but rather a marker for increased risk of invasive breast cancer. There is some controversy about how LCIS should be treated. The treatment options for LCIS are biopsy followed by close follow-up and mammograms every 6 to 12 months, bilateral mastectomy (because the risk of invasive breast cancer is equal for either breast) with breast reconstruction if desired, and chemoprevention with tamoxifen.
Ductal Carcinoma A condition called "atypical hyperplasia" occurs when abnormal cells of the breast cluster. As these cells continue to divide rapidly, changes or mutations can occur in the cells and they can form what is known as "intraductal cancer" or "ductal carcinoma in-situ " (DCIS). Carcinoma in-situ stays "in place" from where it started and has not spread to other areas of the body. Sometimes the word "adenocarcinoma" is used to describe breast cancer. All breast cancers are adenocarcinomas because they all form in the glandular tissue of the breast.
Subtypes of Ductal Carcinoma
Comedocarcinoma: About five percent of breast cancers are comedocarcinoma, a type of ductal carcinoma that completely fills the duct with plugs of tumor growth. Cases in which central necrosis occurs, meaning dead cells are found in the tissue, are described as "comedonecrosis". Comedonecrosis type of breast cancer tends to be more aggressive and invasive.
Medullary Carcinoma: Medullary carcinoma accounts for five to seven percent of all breast cancers and typically affects young women. It is an invasive cancer, but there is a distinct boundary between the tumor and healthy tissue. Although tumors resulting from this type of breast cancer can become very large, the prognosis is more favorable than NOS ductal cancer. However, there is a sub-type of medullary carcinoma called "atypical medullary" that does not have a favorable prognosis.
Mucinous or Colloid Carcinoma: Colloid carcinoma also is known as "mucinous carcinoma" because it is formed by mucous-producing cancer cells. It is slow-growing, can reach bulky proportions, and typically occurs in older women with a long history of breast mass. It is a rare type of invasive breast cancer, accounting for three percent of all breast cancers. Mucinous carcinoma has a low incidence of axillary metastasis and an overall good prognosis.
Tubular Carcinoma: About two percent of breast cancers are tubular carcinoma. Tubular carcinomas have very visible tube-like formations inside the cells. Axillary metastases are rare and the prognosis is considerably better than for NOS ductal carcinoma.
Inflammatory Carcinoma: About one to four percent of breast cancer develop in the lymphatic system of the breast and cause a thickening of the skin covering the breast, making it appear inflamed (reddened or irritated), swollen, thickened, and warm to touch. This type of cancer is called inflammatory breast carcinoma.
In approximately half of the patients, no mass or lump can be felt; but the condition may completely black a duct and form a mass that can be detected on a mammogram. This form of breast cancer is particularly aggressive and may require a combination of all three types of breast cancer treatment: surgery, radiation therapy, and chemotherapy. The prognosis of patients with inflammatory breast cancer is poor, even if the disease is apparently localized.
Paget's Disease: Paget's disease of the breast or Paget's disease of the nipple occurs in one percent of all patients with breast cancer. The patients have a long history of skin changes in the nipple with itching, flaking, burning, oozing, bleeding, or some combination of these symptoms. The nipple changes are due to a cancer in the breast tissue just beneath the surface of the nipple that can be felt in about half to two-thirds of the patients. Cancer cells are often in the nipple itself. The tumor may be an intraductal (noninvasive, in-situ) or invasive ductal type. The prognosis depends on the extent of the cancer and the type of ductal cancer.
Symptoms About 80 percent of breast lumps are benign, particularly those that occur in young women. And most lumps that are tender and painful are not malignant. In fact, before menopause, about half of American women are troubled by lumpy breasts that may become more lumpy and tender just before the menstrual period. (However, don't be falsely reassured that a painful lump is not cancer. The only way to know for certain is with a breast biopsy.)
Sometimes a fluid-filled cyst may form within the breast and feel like a lump. This condition is not really a disease, despite the term "fibrocystic breast disease" (now more appropriately referred to as "fibrocystic condition") that is used to describe it. Nor is it thought to lead to cancer.
Early breast cancer usually does not cause any symptoms or pain. But as the cancer grows, it can cause changes that women should be aware of and watch for:
Any new lump or thickening in or near the breast or underarm area
A change in the breast size or shape
Dimpling or puckering of the breast skin
Swelling, redness, or warmth that does not go away
Pain or tenderness in one spot that does not change with your monthly cycle
Pulling in or puckering of the nipple
A new, sudden nipple discharge that appears only in one breast
An itchy, sore, or scaling area on one nipple
Your doctor should promptly evaluate any of the above symptoms. In most cases, a cancer does not cause them, but they need to be evaluated by a medical professional so that any problems can be detected and treated as early as possible.
The type of treatment selected will depend upon tumor grade and stage as well as your general health. Five types of treatment are commonly used for breast cancer: surgery, radiation, chemotherapy, hormone therapy, and biologic therapy.