Breast cancer is considered "localized" if it is technically possible to excise cancerous tissue, if the tumor does not involve the skin or structures deep to the breast, and if the tumor has not metastasized beyond the axillary or internal mammary lymph nodes.
A variety of prognostic and predictive factors influence the choice of treatment of localized breast cancer, including the status of cancer in the axillary lymph nodes, tumor size, hormone receptor status, HER2/neu status, and a woman's age or menopausal status.
PROGNOSTIC AND PREDICTIVE FACTORS
Lymph node involvement—Fluid from the breast tissue normally drains into lymph nodes located in the axilla, and cancerous involvement of these nodes is an indication of the likelihood that breast cancer has spread and could be present in distant organs. Women with node-positive breast cancer are generally offered chemotherapy, hormone therapy, or both after local treatment, even if the tumor was completely removed. The type of systemic treatment that is recommended depends upon whether the breast cancer expresses hormone receptors and/or the protein HER2/neu.
Size and extent of the tumor—In addition to lymph node status, the prognosis of a breast cancer depends upon its size, since larger tumors (<2 cm) recur more often. In some cases, chemotherapy may be given before surgery to shrink a large tumor (>5 cm) or one that has grown into the chest wall.
Histology—There are several histologic types of breast cancer. However, from the standpoint of treatment, the most important distinction is between invasive and noninvasive (in situ) breast cancer. The surgical treatment of in situ cancers is similar to that of invasive cancers, but axillary nodal dissection is generally not recommended.
Hormone receptor status—Estrogen receptor (ER) and progesterone receptor (PR) assays are routinely performed by pathologists on tumor material. Women with hormone receptor-positive tumors benefit from postoperative endocrine treatments such as tamoxifen, or in postmenopausal women, the aromatase inhibitors (anastrozole, letrozole, or exemestane). For premenopausal women, ovarian ablation or suppression can be considered, but evidence regarding its efficacy from randomized clinical trials is currently lacking. Hormone therapy is not beneficial for women with hormone receptor-negative tumors.
HER2/neu status—Assays for HER2/neu status are routinely performed on the tumor material. Women with invasive tumors that overexpress HER2/neu benefit from postoperative trastuzumab, a monoclonal antibody directed at HER2/neu.
Age and/or menopausal status—Women who are under the age of 50 years or premenopausal at the time of breast cancer diagnosis derive more benefit from adjuvant systemic chemotherapy than postmenopausal women. Postmenopausal women have a lesser absolute benefit in reduction of recurrence risk than premenopausal women but still can have some benefit from adjuvant chemotherapy.
SURGERY FOR LOCALIZED BREAST CANCER
Generally, surgical options for women with localized breast cancer include breast conserving therapy (BCT) and irradiation or mastectomy.