Malignant Conditions of the Breast
Breast cancer is a major health problem in the United States. Its overall incidence rose by 54% between 1950 and 1990. In the 1990s, the incidence leveled off and stabilized (American Can-cer Society [ACS], 2002). At present, there is no cure for breast cancer. Between 1990 and 1994, the mortality for breast cancer decreased by 5.6%, the largest short-term decline in more than 40 years, suggesting that the combination of early detection and better systemic treatment options is having an effect on overall survival.
Current statistics indicate that a woman’s lifetime risk for de-veloping breast cancer is 1 in 8, but this risk is not the same for all age groups. For example, the risk for developing breast cancer by age 35 years is 1 in 622; the risk for developing breast cancer by age 60 years is 1 in 23. Approximately 80% of breast cancers are diagnosed after the age of 50. According to the American Cancer Society, more than 193,000 cases of breast cancer are diagnosed each year, with an estimated 40,000 deaths. About 1% of these cancers occur in men. Women who are diagnosed with early-stage localized breast cancer have a 5-year survival rate of 98% (ACS, 2002).
In situ carcinoma of the breast is being detected more frequently with the widespread use of screening mammography. Since the in-troduction of widespread mammographic screening over the past two decades, ductal carcinoma in situ (DCIS) has accounted for approximately 20% of diagnosed breast cancers (Winchester, Jeske & Goldschmidt, 2000). This disease is characterized by the proliferation of malignant cells within the ducts and lobules, with-out invasion into the surrounding tissue; therefore, it is a non-invasive form of cancer and is considered stage 0 breast cancer. There are two types of in situ carcinoma: ductal and lobular.
DCIS, the more common of the two types, is divided histologi-cally into two major subtypes (comedo and noncomedo), but there are many different forms of noncomedo DCIS. Because DCIS has the capacity to progress to invasive cancer, the most traditional treatment is total or simple mastectomy (removal of the breast only), with a cure rate of 98% to 99% (Winchester et al., 2000). The use of breast-conserving surgery for invasive cancer led to the use of breast-conservation therapy (limited surgery followed by radiation) for patients with DCIS, and this option is appropriate for localized lesions. More than half of cases of DCIS are now being treated with breast-conservation therapy; however, the rate of local recurrence is 15% to 20% (Solin, Fourquet, Vicini et al., 2001). In some cases, lumpectomy alone is an option, but this is decided on a case-by-case basis. In 1999, a large study demonstrated that tamoxifen (Nolvadex) significantly reduced local recurrence rates (Fisher, Dignam, Wolmark et al., 1999). Following this, the FDA approved the use of tamoxifen for women with DCIS after treatment with surgery and radiation. It is usually prescribed for 5 years.
LCIS is characterized by proliferation of cells within the breast lobules. LCIS is usually an incidental finding discovered on pathologic evaluation of a breast biopsy for a breast change noted during physical examination or on screening mammography. It is commonly associated with multicentric disease and is rarely associated with invasive cancer. Historically, treatment was bi-lateral total mastectomy, but current thinking that LCIS is a marker of increased risk for the development of an invasive cancer (rather than an actual malignancy) has changed this ap-proach. Long-term surveillance is one appropriate option. An-other option is a bilateral prophylactic mastectomy to decrease risk; current research (Hartmann et al., 1999) suggests that a 90% reduction in risk is possible with this option. The other treatment option for LCIS is chemoprevention. In fall 1998, the FDA approved the use of tamoxifen (Nolvadex) as a chemopreventive agent prescribed for 5 years for women at high risk; however, as with any drug, tamoxifen has both benefits and risks, along with possible side effects.
Infiltrating ductal carcinomas are the most common histologic type of breast cancer and account for 75% of all breast cancers. These tumors are notable because of their hardness on palpation. They usually metastasize to the axillary nodes. Prognosis is poorer than for other cancer types.
Infiltrating lobular carcinoma accounts for 5% to 10% of breast cancers. These tumors typically occur as an area of ill-defined thickening in the breast, as compared with the infiltrating ductal types. They are most often multicentric; that is, several areas of thickening may occur in one or both breasts. Infiltrating ductal and infiltrating lobular carcinomas usually spread to bone, lung, liver, or brain, whereas lobular carcinomas may metastasize to meningeal surfaces or other unusual sites.
Medullary carcinoma constitutes about 6% of breast cancersand grows in a capsule inside a duct. This type of tumor can be-come large, but the prognosis is often favorable.
Mucinous cancer accounts for about 3% of breast cancers. A mucin producer, it is also slow-growing and thus has a more favorable prognosis than many other types.
Tubular ductal cancer accounts for only 2% of cancers. Because axillary metastases are uncommon with this histology, prognosis is usually excellent.
Inflammatory carcinoma is a rare type of breast cancer (1% to 2%) with symptoms different from those of other breast cancers. The localized tumor is tender and painful, and the skin over it is red and dusky. The breast is abnormally firm and enlarged. Often, edema and nipple retraction occur. These symptoms rapidly grow more severe and usually prompt the woman to seek health care sooner than the woman with a small breast mass. The disease can spread to other parts of the body rapidly; chemotherapeutic agents play a major role in attempting to control the progression of this disease. Radiation and surgery are also used to control spread.
Paget’s disease of the breast accounts for 1% of diagnosed breastcancer cases. A scaly lesion and burning and itching around the nipple–areola complex are frequent symptoms. The neoplasm is ductal and may be in situ alone or may also have invasive cancer cells. Often, a tumor mass cannot be palpated underneath the nipple where this disease arises. Mammography may be the only diagnostic test that detects the tumor, but results of the mam-mogram are often negative, making biopsy of the lesion the only definitive test.
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