The sentinel lymph node biopsy in breast cancer

To evaluate the possibility and accuracy of this new diagnostic approach to the breast cancer disease in our centre.

Since March 1999, every patient presenting with a cT1-T2 N0 breast carcinoma was scheduled for a sentinel lymph node search. An injection of Tc-99 labelled nanocolloïd with a dose of 1 mCu was injected either intramammary or intradermally. The patients have been divided into two groups: in group I, they received their injection intramammarily the day before the operation; because of several failures in identifying the sentinel lymph node (SLN), the protocol was modified, the patients receiving their injection the day of operation, intradermally (group II). Once a lymphoscintigraphy done, the SLN was identified at operation using a detection probe, after the primary tumour had been removed. A routine axillary dissection was then performed to remove the rest of the lymph nodes. All the nodes were then checked routinely for metastatic cells. The SLN was also screened by semi-serial slides and by immuno-assay.

From March 1999 till March 2001, sixty patients presented consecutively with a T1 or T2 biopsy proven breast carcinoma with no clinical lymph nodes. They were all scheduled for a sentinel lymph node search according to the protocol. Mean tumour size was 9.9 mm (ranging from 4 to 23 mm). Fourteen patients (group I) received their injection intramammarily but we failed to identify the sentinel node in five patients (35%). The remaining forty-two patients (group II) received their injection intradermally. Sentinel nodes were then identified in forty-three patients (93%). Positive SLN were discovered in eleven cases by routine examination (13 positive nodes among 104 harvested sentinel nodes, i.e. 13%). Micro metastases were discovered in three other SLN by immunohistology. In total, 605 lymph nodes were evaluated through the axillary dissection, representing a mean number of 10.08 lymph nodes per patient. For four patients, positive lymph node were discovered in the axillary dissection while SLN were negative (6.6% of false negative).

During this learning curve period, it appears that the method for screening the SLN is reliable, since the figures encountered are similar to those of the literature. By adding a perioperative blue dye injection, it might be possible to reduce the percentage of false negative results. It is difficult to assess, at present, the impact SLN could have on survival.