Detection Of Metastatic Foci In Internal Mammary Nodes And Its Clinical Significance For Patients With Breast Cancer

Objective To investigate a convenient surgical approach to internal mammary nodes biopsy and analyze the utility of detection methods for small metastatic foci in such nodes, then evaluate the clinical significance of pathological examination of internal mammary nodes.Methods 100 female patients with unilateral breast cancer underwent modified radical mastectomy without initial radiotherapy and chemotherapy were included from July 2006 to May 2008. Surgical approach to the second and third ipsilateral intercostal spaces was done after excising the mamma and clearing axillary lymph nodes. Internal mammary nodes resected were routinely underwent haematoxylin and eosin(HE) staining on one slice. If there was no positive metastatic sign observed in the node, step serial sectioning(SSS) plus HE staining and immunohistochemistry(IHC) detection for CK19 and EMA expression will be plunged to purchase small metastatic foci.Results①94 cases were successfully biopsied in their intercostal spaces, and a total of 147 internal mammary nodes were harvested with an average of 1.56±0.69 nodes(range, 1~4) for each one. The achievement ratio of biopsy was up to 94% with 95% confidence interval covered 89.3% to 98.7%.②6 cases with 12 nodes underwent routine HE staining on one slice revealed metastases in 10 nodes. The rest 88 cases with 135 negtive nodes further underwent SSS plus HE and IHC, and 5 of them with 6 nodes revealed small metastatic foci, that is, 1 case with 1 node was visualized micrometastases both by HE and IHC, the other 4 cases with 5 nodes just revealed isolated tumor cells/clusters only by IHC, among which, 1 node from 1 case of infiltrating lobular carcinoma was visualized isolated tumor cells dispersed in a diffuse pattern. For detecting small metastatic foci in the lymph node, there was statistical significance of goodness of fit between HE and IHC after SSS(P<0.01), but the consistency was weak(Kappa value<0.40).③A total of 11 cases detected pathologic positive internal mammary nodes were all upstaged with their postoperative pathologic N stagings.④Location of the primary tumor and number of the axillary lymph nodes correlate with the pathological status of internal mammary nodes according to univariate analysis(P<0.05), in the following multivariate analysis, different numbers of positive axillary lymph nodes make different senses to the pathological status of internal mammary nodes after excluding the confounding factor——primary tumor location(Wald chi-square value=7.912, P=0.048).Conclusion①Surgical approach to internal mammary nodes biopsy through intercostal space is a feasible way without increasing postoperative complications and morbidities.②It is essential to make detail pathological examination of an internal mammary node to discover additional small metastatic foci, such applying SSS plus HE and IHC could reduce missed diagnosis.③Detail pathological examination of internal mammary nodes could further precisely classify postoperative pathologic N staging.④Different numbers of positive axillary lymph nodes make different senses to the pathological status of internal mammary nodes, while location of the primary tumor may possibly make influence along with condition of the axillary lymph nodes to the pathological status of internal mammary nodes.