Summary:
The sentinel lymph node (SLN) is defined as the first node(s)
receiving lymphatic drainage from a primary tumour. A
promising alternative to axillary lymph node dissection
(ALND) is sentinel lymph node biopsy. SLN biopsy has been
introduced as a technique to identify axillary lymph node
most likely to contain tumour cells metastasizing from a
primary carcinoma of breast. Several methods of identifying
the SLN exists, including the use of radioactive tracer,
lymphazurin dye or combination of the two via
intraparenchymal and/or intradermal, peritumoral or
periaerolar injection sites. Intraoperative evaluation of SLNs
are done by performing FS(Frozen Section) on all the lymph
nodes after serially sectioning them at 3-4mm intervals; at
least 2 levels are cut of all the sentinel lymph nodes. In
addition, touch preparation cytology(TP) smear may also
be made for evaluation. The limitations of SLNB is that a
proportion of patients who have metastasis limited to the
SLN can be predicted when there is a combination of tumour
size <1.0cm, the absence of lymphovascular invasion and
micrometastatic disease (<0.2cm) in SLN. However for
patients with large breast cancer, the role of SLNB is
controversial. Early studies of SLNB in large breast cancer
patients demonstrated a high (8-18%) false negative rate,
with the accuracy worsening with the increasing size.
Excision of SLNs have an extremely low morbidity and a
high degree of staging accuracy. A tumour-free SLN
virtually excludes lymphatic involvement of the entire
regional lymphatic basin. More than 50 observational
studies of SLNB validated by a back up ALND demonstrate
that SLNB is feasible, accurate and suitable for virtually
all patients with operable clinically node negative disease.
Sentinel lymph node biopsy not only provide prognostic
information, but also aims to guide adjuvant therapy without
the untoward side effects of complete axillary dissection.
Key words: Sentinal lymph node, Management, Breast Cancer.