One of the most important prognostic factors in early breast cancer is spread to axillary nodes. Sentinel lymph node biopsy is now widely used to determine the need for axillary node dissection. Chung and colleagues followed women with negative sentinel node biopsies to determine the rate of false-negative results.

Since 1998, the authors' institution has used a breast cancer treatment protocol that includes sentinel lymph node biopsy in patients with ductal carcinoma in situ or invasive breast cancer less than 3 cm in diameter with clinically negative axillary nodes. If the sentinel node was negative, no axillary dissection was performed. Most patients who had breast-conserving surgery underwent adjuvant whole-breast irradiation. Depending on tumor characteristics, adjuvant chemotherapy or hormonal manipulation was recommended. All patients were reexamined every three months, and mammography was performed every six months. Suspicious lesions were investigated further by radiography or surgery.

During the four-year study, 324 women underwent sentinel node biopsy. Patients were excluded from the study if a sentinel node could not be identified, primary breast cancer was not confirmed, a sentinel lymph node was positive, previous axillary surgery had been performed, or previous adjuvant therapy had been given. Sentinel node biopsies were positive in 84 patients.

The 207 women with negative sentinel nodes were followed for a median of 26 months. The average age of these women was 56 years, and the median primary tumor size was 1.2 cm. Most of the patients (91 percent) underwent breast-conserving surgery, and 60 percent received adjuvant systemic therapy or anti-hormonal therapy.

Six patients developed recurrent disease during the follow-up period. Three of the recurrences involved the axilla. The authors calculated the false-negative rate of sentinel lymph node biopsy to be 1.4 percent. Although the follow-up time in the study was relatively short, it is longer than the median time to regional breast cancer recurrence (19 months). The authors conclude that sentinel node biopsy is a safe, minimally invasive procedure that can accurately identify axillary metastasis with a low clinical recurrence rate.