Sentinel node biopsy in the evaluation of the internal mammary node chain in patients with breast cancer

In patients with breast cancer the presence of internal mammary chain (IMC) metastases changes tumor staging, and the occurrence of IMC drainage is quite common in breast cancer. Nevertheless, IMC dissection is not a routine procedure in modern surgical approaches towards breast cancer. We therefore need minimally invasive techniques for accurate assessment of the IMC nodal basin. The aim of this study was to investigate whether sentinel node biopsy (SLNB) could offer a solution.

From November 1997 to June 2001 143 female patients who were eligible for breast cancer surgery were included in the study. All patients had T1 breast cancer and clinically negative axillae. Patients were submitted to preoperative lymphoscintigraphy with subsequent SLNB. We used a 99m-technitium nanocolloid tracer (Nanocoll) that was injected peritumorally so as to have about 10 MBq of radioactivity at the time of surgery. Scintigraphy was performed about 17 hours after tracer administration. During surgery, lymphoscintigraphic imaging and a gamma ray detection probe were used to locate the sentinel node. Histological examination after embedding in paraffin was usually requested and multilevel sectioning of the sentinel node (SLN) was performed, with hematoxylin and eosin staining and immunohistochemistry.

Preoperative lymphoscintigraphy localized SLNs in the IMC basin in 27 of 143 patients (18.9%). Harvesting of IMC-SLNs based on lymphoscintigraphy results was successful in 20 of 27 patients (74.1%). Histological examination revealed micrometastases in four of the 20 harvested nodes. One of these patients showed no axillary drainage and no axillary lymph node dissection was therefore performed. In the remaining three patients also axillary SLNs were harvested, which turned out to be free from metastatic involvement.

In our experience lymphoscintigraphy with SLNB was an accurate method to detect IMC metastases in patients with breast cancer. We recommend peritumoral tracer injection and a reasonable interval between injection and scintigraphy. IMC-SLN biopsy did not result in any serious additional complications or morbidity. In our study this approach led to improved cancer staging: four of 20 harvested IMC-SLNs proved to be micrometastatic. None of these four patients had metastatic axillary SLNs. Exclusive drainage to the IMC is present in only a small number of breast cancer patients, and our results suggest that it is possible to avoid unnecessary axillary node dissection in such cases.