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

Background: The prognostic meaning and thus indication for adjuvant therapy of lymphogenic micrometastases in breast cancer patients is still under debate. Patients and methods: From 1999 to 2007, 703 patients with cT1-2N0 breast cancer underwent surgery including sentinel lymph node biopsy. Examination of sentinel lymph nodes consisted of hematoxylin and eosin and immunohistochemistry staining following serial sectioning of the sentinel node. Patients were divided into four groups: N-p(0) (n = 423), N-p(1micro) (n = 81), N-p(1a) (n = 130) and N-p(>= 1b) (n = 69). Median follow-up was 40 months. Results: At the end of follow-up, 53 patients had died and 64 had recurrent disease. Compared with N-p(0) and following adjustment for possible confounders, including adjuvant systemic treatment, overall survival was not significantly different for N-p(1micro) while significantly worse for N-p(1a) and N-p(>= 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 different for N-p(1micro) and worse for N-p(1a) and N-p(>= 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 observed in the N-p(1micro) than in the N-p(0) group, but still not as common as in the N-p(1a) or N-p(>= 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 higher in patients in the N-p(1micro) than in the N-p(0) group, no statistically significant differences were observed in overall or disease-free survival between N-p(0) and N-p(1micro). Micrometastatic lymph node involvement in itself should not be an indication for adjuvant chemotherapy in breast cancer patients.