Prognostic value of micrometastases in sentinel lymph nodes of patients with breast carcinoma: a cohort study

Background: The prognostic meaning and thus indication for adjuvanttherapy of lymphogenic micrometastases in breast cancer patientsis still under debate. Patients and methods: From 1999 to 2007, 703 patients with _cT_1–2N₀breast cancer underwent surgery including sentinel lymph nodebiopsy. Examination of sentinel lymph nodes consisted of hematoxylinand eosin and immunohistochemistry staining following serialsectioning of the sentinel node. Patients were divided intofour groups: _pN₀ (n = 423), _pN_1micro (n = 81), _pN_1a (n = 130)and _pN_1b (n = 69). Median follow-up was 40 months. Results: At the end of follow-up, 53 patients had died and 64had recurrent disease. Compared with _pN₀ and following adjustmentfor possible confounders, including adjuvant systemic treatment,overall survival was not significantly different for _pN_1microwhile significantly worse for _pN_1a and _pN_1b {hazard ratio (HR)[95% confidence interval (CI)]: 0.59 [0.14–2.58], 4.31[1.85–10.01], 10.66 [4.04–28.14], respectively}.Likewise, disease-free survival was not significantly differentfor _pN_1micro and worse for _pN_1a and _pN_1b (HR [95% CI]: 1.43[0.67–3.02], 2.79 [1.37–5.66], 7.13 [3.27–15.54],respectively). Distant metastases were more commonly observedin the _pN_1micro than in the _pN₀ group, but still not as commonas in the _pN_1a or _pN_1b group (HR [95% CI]: 4.85 [1.79–13.18],10.34 [3.82–28.00], 23.25 [7.88–68.56], respectively). Conclusion: Although the risk of distant metastases was higherin patients in the _pN_1micro than in the _pN₀ group, no statisticallysignificant differences were observed in overall or disease-freesurvival between _pN₀ and _pN_1micro. Micrometastatic lymph nodeinvolvement in itself should not be an indication for adjuvantchemotherapy in breast cancer patients. Key words: breast cancer, micrometastases, prognosis, sentinel lymph nodeReceived for publication March 11, 2008. Revision received June 25, 2008. Accepted for publication July 1, 2008.