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In invasive or infiltrating breast cancer, lymph nodes from the axilla are removed at the time of surgery to determine if the cancer has spread beyond the breast tissue. The surgeon may remove all of the lymph nodes (total axillary dissection), or in many facilities, a new procedure — sentinel node dissection — has gained acceptance as the preferred treatment. In this procedure, blue dye and a radioactive tracer are injected near the tumor bed preoperatively. The surgeon is able to identify the first node or the first few nodes in the lymphatic basin that drains the tumor using a handheld Geiger counter. He or she then removes that node(s), and the pathologist examines the tissue in the OR by frozen section analysis. If the node is “clean,” no further dissection of lymph nodes is necessary. Avoiding dissection of several nodes greatly reduces the chances of problems after surgery, such as compromised arm movement and/or lymphedema.

Tissue removed during surgery is submitted for microscopic analysis that further characterizes the cancer. Type, tumor size, grade, invasion, lymphocytic response, and clean margin size all give valuable information to help develop a treatment plan. Staging of the tumor provides information based on TNM categories: T (Tis – T4) defines the size of the tumor. N (N0-N3) refers to whether the cancer is in adjacent lymph nodes, and M (M0-M1) indicates the presence or absence of metastasis. Additional testing, such as hormone receptor status (estrogen and progesterone positive or negative) and HER2/neu (hsuman epidermal growth factor receptor 2) expression, also helps the oncologist plan subsequent adjuvant therapies.

Radiation and chemotherapy

If radiation alone is needed, the treatments begin after a reasonable time for healing of the surgical site. To kill cancer cells not removed by surgery, patients undergo external beam radiation to the affected chest wall and axilla. The usual treatment course runs five days a week for about six weeks, with a “boost” in radiation usually given during the last week of treatment. Patients usually tolerate the radiation well, with fatigue and/or skin changes as the primary side effects.

Chemotherapy may be indicated for patients when tumors are greater than 1 cm, lymph nodes are positive for cancer cells, or the cancer is of a high histologic grade that may indicate a more aggressive type. The major categories of breast cancer drugs work by destroying cells during cell growth or division. Anthracylines, such as doxorubicin (Adriamycin, 60 mg/M²), interfere with the DNA of the tumor cells.

The alkylating agent cyclophosphamide (Cytoxan, 600 mg/M²) interferes with DNA reproduction. The antimetabolites methotrexate (40 g/M²) and 5-fluorouracil (600 mg/M²) interfere with the S-phase of cell mitosis.² A newer class of drugs, the taxanes, inhibit mitosis during the M part of the cell cycle. Paclitaxel (Taxol, 135-175 mg/M²) and docetaxol (Taxotere, 60-100 mg/M²) are taxanes derived from the bark and needles of the yew tree. Various combinations of all these and other drugs can be used concurrently or consecutively to maximize cell kill. The oncologist can adjust treatment based on the patient’s response. Newer therapies include dose-dense treatments in which patients receive chemotherapy at shorter intervals without appreciable adverse effects.

Each category of drug comes with its own set of adverse effects. However, these can be more effectively managed today with the use of antinausea drugs like granisetron hydrochloride (Kytril) and ondansetron (Zofran). In addition, growth stimulating factors, such as epoetin alfa (Procrit) and filgrastim (Neupogen), keep red and white blood cell counts from plummeting to dangerously low levels.

Hormone therapy is currently used to block circulating estrogens that could potentially accelerate growth in estrogen-positive tumors. In postmenopausal women with estrogen-receptor-positive breast cancer, nolvadex, (Tamoxifen, 20 mg q day x 5 years) has been the gold standard. More recently, the aromatase inhibitor anastrozole (Arimidex, 1 mg qd x 5 years) has been used successfully to shut down the production of endogenous estrogen; other aromatase inhibitors, such as letrozole (Femara, 2.5 mg qd) and exemestane (Aromasin, 25 mg qd), are being studied.

Breast cancers that overexpress the protein HER2/neu may be associated with a more aggressive form of disease and a poorer prognosis. The first humanized monoclonal antibody, trastuzumab (Herceptin, 2-4 mg/kg IV infusion), is currently being used to treat patients that overexpress HER2/neu.

Although patients with breast cancer may be overcome by anxiety, anger, depression, and indecision, they learn quickly that a team of expert radiologists, nurses, general and plastic surgeons, pathologists, and medical and radiation oncologists will stand by them, planning care tailored to their particular situation and thus offering them the best chance for long-term survival.

Sue R. Holmes , RN, BHS, is the breast health coordinator at deNicola Breast Health Center at Southern New Hampshire Medical Center, Nashua.

References

1. Breast cancer treatment guidelines for patients: version v. National Comprehensive Cancer Network website. Available at: www.nccn.org/patients/patient_gls/_english/_breast/index.htm. Accessed Aug. 6, 2004.