[Sentinel node biopsy in breast cancer. Improving reliability of results]

Sentinel node (SN) biopsy in breast cancer has a relatively high false negative rate, frequently exceeding 10%, for predicting the axillary nodal status. When the SN is identified using the patent blue dye technique, we advocate subjecting it to a verification of its blue colour by the pathologist as quality control.

One hundred and twenty-two consecutive patients with an operable breast cancer underwent a SN biopsy procedure with patent blue dye injected peritumourally. The SN biopsy was routinely followed by an axillary dissection. Initially each SN was examined histopathologically in a standard fashion. Then the non metastatic SNs were checked to ensure that they were blue by macroscopic examination of the paraffin blocks in which they had been embeded. Finally, a search for micrometastasis using immunohistochemistry was performed on all SNs which were non metastatic and confirmed to be blue.

In 107 (88%) of 122 patients a SN was identified by the surgeon. After standard histological examination, 32 of 107 SNs proved to contain metastatic tumour. 75 SNs were not metastatic, of which 3 were false negative which would have given a false negative rate of 8.5%(3/35). After checking the paraffin blocks of the 75 non metastatic SN, 62 of the 75 were confirmed blue from which there were 2 false negatives giving a false negative rate of 5.8% (2/34). The 62 confirmed blue nodes were then assessed for micrometastasis. 20 nodes proved to be micrometastatic and there remained one false negative. This gave a final false negative rate of 1.8% (1/53). The false negative rate was thus reduced from 8.5% to 1.8% after colour quality control and identification of micrometastasi.

In this series the procedure of histopathological quality control of the SN identified with the patent blue only technique resulted in a valuable reduction in the false negative rate.