Sentinel node in breast cancer: retrospective analysis of 212 patients and factors associated with lymphatic involvement

Objective

To perform a retrospective study/review of the sentinel lymph node biopsy (SLNB) technique at our institution, analysing (from the results obtained) the relationship with the patients' age, tumour characteristics, injection technique, lymph node involvement and local/regional recurrence.

Materials and methods

A total of 212 patients were included; 209 patients underwent subdermal periareolar injection (of ^99mTc nano-colloid) and peritumoral injection was performed in three patients. Lymphoscintigraphy was performed after 15 to 30 minutes post-injection until the sentinel lymph nodes (SLN) were identified, and anterior and lateral views were registered. In the case of a next-day surgery protocol, a delayed 24-hour post-injection view was registered preoperatively. Skin marking of the SLN location was performed preoperatively. SLN were defined as the ones presenting with the highest count rate as measured by the intraoperative probe, as well as those with count rate of at least >10% of the former. The remaining resected LN were regarded as non-SLN (NSLN). A descriptive (and association) analysis of the following variables was performed: age, size and tumour location, histology type and grade, injection technique, number of removed SLN and NSLN, malignant involvement of SLN and NSLN, surgical axillary clearance (AC), malignant lymphadenopathy in AC and axillary recurrence.

Results

The mean patient age was 59 (range 32 to 85) years; mean of removed SLN 2.94; mean of removed NSLN 0.82. The primary tumour was palpable in 115 patients (54.25%). The most frequent location was the supero-external quadrant (45.75%). The size of most tumours was between 1 and 2 cm (34.43%). The most common histological group was ductal carcinoma (60.38%) and the most common histology grade was 2 (37.74%). In 91.08% of cases, the number of removed SLN was ≤ 5. SLN were positive in 49 patients (23.11%). In 92.45%, ≥ 3 NSLN were removed. In six patients (2.83%) the NSLN were positive on histology, and in three of them SLN were negative. There was a statistically significant relationship between tumour size and malignant involvement of the SLN and NSLN, the indication of AC and the presence of malignant lymphadenopathy in AC. Moreover, there was a statistically significant relationship between histology grade and the number of removed SLN.

Conclusion

The local and regional lymph node involvement of disease only showed a statistically significant relationship with tumour size. The number of removed SLN showed a statistically significant relationship with histology grade. It would be advisable to perform a histological analysis of all removed SLN and NSLN.