Abstract S5-2: Iatrogenic Displacement of Tumor Cells to the Sentinel Node after Surgical Excision Biopsy in Primary Breast Cancer

Abstract

Abstract Background: It is shown that isolated tumor cells are more common in the sentinel node after needle biopsy of a breast cancer, indicating iatrogenic displacement of epithelial cells. This may result in unnecessary axillary lymph node dissections. It is possible that a similar iatrogenic displacement occurs after surgical excision biopsy but the incidence and clinical significance is basically unknown. Material and Methods: By linking data from the Danish Breast Cancer Cooporative Group database and data from the Danish National Health Registry we compared the incidence of isolated tumor cells and micrometastases in the sentinel node of 347 breast cancer patients with prior surgical excision biopsy to a group of 14401 patients without prior surgical excision biopsy in a multivariate analysis adjusting for tumor size, receptor status, type and histological grade. The incidence of isolated tumor cells in the sentinel node was further analysed by histological type. Finally, we investigated the incidence of non-sentinel node metastases in patients with isolated tumor cells and micrometastases in the sentinel node after prior surgical excision biopsy. Results: We found an adjusted odds ratio on 3.99 (95% CI 2.67-5.97; P<0.0001) for having isolated tumor cells in the sentinel node after surgical excision biopsy. Likewise, we found an adjusted odds ratio for having micrometastases on 1.62 (95% CI 1.20 -2.18; P=0.002). Isolated tumor cells were, in general, more common in the sentinel node of lobular carcinomas compared to ductal carcinomas (adjusted OR 3.51; 95% CI 2.80-4.40; P<0.0001). In contrast, the increase in isolated tumor cells after surgical excision biopsy was especially seen in patients with ductal carcinomas with an adjusted odds ratio on 5.41 (95% CI 3.45-8.48; P=0.054) whereas the odds ratio for lobular carcinomas was only 1.53 (95% CI 0.45-5.14) (P=0.054 for heterogeneity). None of the 20 patients with isolated tumor cells in the sentinel node after prior surgical excision biopsy had non-sentinel node metastases compared to 13% in the group without prior surgical excision biopsy (P=0.15). In patients with micrometastases in the sentinel node after prior surgical excision biopsy 13% had non sentinel node metastases compared to 18% in the group without prior surgical excision biopsy (P=0.29). Conclusions: The 4-fold increase in isolated tumor cells in the sentinel node after surgical excision biopsy indicates that this procedure induces iatrogenic displacement of epithelial cells. This displacement is more common in ductal carcinomas, despite the fact that lobular carcinomas, in general, are more likely to present with isolated tumor cells in the sentinel node. We found no further dissemination to non-sentinel lymph nodes, suggesting that isolated tumor cells in the sentinel node in these women do not indicate further spread of disease. Hence, in case of isolated tumor cells in the sentinel node after prior surgical excision biopsy, omission of axillary lymph node dissection should be considered. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr S5-2.