Patients whose sentinel node biopsy is normal do not require a complete node dissection, because the risk of an axillary recurrence is extremely low. Many institutions are using IHC in the evaluation of the sentinel node. When there is no evidence of metastatic disease by routine hematoxylin and eosin staining and the node is IHC−, the node is considered pN0 (i−). When there are isolated tumor cells seen but no cluster is greater than 0.2 mm, the node is staged as pN0 (i+) and the patient does not require a complete node dissection. If the focus of metastatic disease in the node is greater than 0.2 mm but less than 2 mm, the node is staged as pN1mi. In this instance, consideration should be given to performing a complete axillary node dissection or axillary radiation therapy, unless the patient is participating in a clinical trial. The likelihood that nonsentinel lymph nodes will also contain metastatic disease increases as the size of the primary tumor increases.

Radiation therapy after breast-conserving surgery

Based on the results of a number of retrospective single-institution experiences, as well as several prospective randomized clinical trials, breast-conserving surgery followed by radiation therapy to the intact breast is now considered a standard treatment for the majority of patients with stage I or II invasive breast cancer.

Radiation dose and protocol Radiation therapy after breast-conserving surgery should employ careful treatment planning techniques that minimize treatment of the underlying heart and lungs. To achieve the optimal cosmetic result, efforts should be made to obtain a homogeneous dose distribution throughout the breast. Doses of 180 to 200 cGy/d to the intact breast, to a total dose of 4,500 to 5,000 cGy, are considered standard.

Additional irradiation to the tumor bed is often administered. Although the necessity of a boost to the tumor bed has been questioned, at least two randomized clinical trials have demonstrated a small but statistically significant reduction in ipsilateral breast tumor relapses with the use of a radiation boost to the tumor bed following whole-breast irradiation of 50 Gy. In one of these trials, involving more than 5,000 women randomized to receive either a 16-Gy boost to the tumor bed or not, a 3% absolute reduction in local relapse was seen with the use of the radiation boost (4.3% vs 7.3%; P < .0001). This effect was particularly evident in patients younger than age 50. The boost is directed at the original tumor bed with either electron-beam irradiation or an interstitial implant, to bring the total dose to 50 to 66 Gy.

Regional nodal irradiation For patients who undergo axillary dissection and are found to have negative nodes, regional nodal irradiation is no longer routinely employed. For patients with positive nodes, radiation therapy to the supraclavicular fossa and/or internal mammary chain may be considered on an individualized basis (see chapter 10).

Partial breast irradiation There have been several reports demonstrating promising results with the use of partial breast irradiation, a potentially more convenient option for patients than the extended course of postoperartive radiotherapy.

Additional options are now available to shorten the radiotherapy treatment time to 1 to 5 days (accelerated) and to focus an increased dose of radiation on just the breast tissue around the excision cavity (partial breast). Current accelerated partial breast irradiation (APBI) approaches include interstitial brachytherapy, intracavitary (balloon) brachytherapy, and accelerated external beam (three-dimensional conformal) radiotherapy. Intraoperative radiotherapy is even shorter, with the entire treatment given as a single dose delivered immediately after surgery. Each approach has benefits and limitations.

Ongoing randomized trials will shape how APBI is utilized in routine clinical practice. Some of the more important outcomes from these trials will be local toxicity, local and regional recurrence, and overall survival. If APBI is ultimately demonstrated to be as safe and effective as whole-breast radiotherapy, breast conservation may become an even more appealing choice, and the overall impact of treatment may be further reduced for certain women with newly diagnosed breast cancer.

Mastectomy options

Patients who are not candidates for breast conservation or who are not interested in breast conservation are offered mastectomy. For patients who desire immediate reconstruction at the time of mastectomy, a skin-sparing approach is recommended, provided it is oncologically safe. In most instances, the mastectomy can be performed through a circumareolar incision, where the nipple-areolar complex (NAC) is excised in continuity with the breast tissue. If a biopsy has been performed, this skin should also be excised with the mastectomy specimen. There have been reports in the literature in which the NAC has been spared during the course of a skin-sparing mastectomy. This concept awaits further study and is not considered standard of care.

MEDICAL TREATMENT

Medical management of local disease depends on clinical and pathologic staging. Systemic therapy is indicated only for invasive (infiltrating) breast cancers.

In the past, systemic therapy was not offered to patients with stage I disease (tumors up to 2.0 cm). However, adjuvant chemotherapy and hormonal therapy have been shown to improve disease free and overall survival in selected patients with node-negative disease.