Injection Techniques
There is nevertheless significant variation in
the rate of detection of internal mammary lymph
nodes and this seems to be dependent on the
mode of administration of the colloid. The sub-
dermal injection technique is associated with
the lowest detection rate of internal mammary
nodes, and higher detection rates are report-
ed with an intratumoral and a peritumoral ap-
proach.
It is the aim of this chapter to describe the
prac-
tical aspects of various injection techniques.
Palpable Breast Carcinoma
Patient Selection
The patient selection criteria for the sentinel
node
biopsy trial conducted at our Institution for
breast
cancer are as follows:
Eligibility Criterion:
1. Proven palpable or non-palpable invasive car-
cinoma of the breast on “triple assessment”, i.e.
clinical examination, imaging (mammogram
and ultrasound) and tissue diagnosis (cyto-
logy, Tru-cut biopsy), where surgical treatment
would involve removal of the primary tumour
and axillary dissection
Breast Carcinoma
There is as yet no single accepted method for sen-
tinel node localisation, and there are significant
variations in the injection technique used for the
administration of radionuclide colloids. The tech-
niques range from single subdermal injection
[1] to multiple peritumoral [2 –6] and even intra-
tumoral injection [7]. Other variables (described
elsewhere in the book) include the type of
colloidal
particles used, with special emphasis on particle
size [8] and the volume [9, 10] of the injectate.
In
brief, with a small particle size the risk of
sampling
non-sentinel nodes is increased due to spill-over
of
the colloid to other nodes, leading to sampling of
an
increased number of lymph nodes [3,11]; on the
other hand,with a larger particle size the
transport
may be inadequate, resulting in a higher sentinel
node detection failure rate.Despite variation in
the
techniques used for sentinel node localisation,
the
overall results are encouraging. In a recent com-
bined analysis by McMasters and co-workers [12],
in
1385 patients with breast carcinoma the overall
sensitivity was 94% and the specificity 100% when
the sentinel node histology was compared with the
axillary node dissection specimen. The overall
accuracy reported in this combined analysis was
98
%, with a positive predictive value of 100% and
a
negative predictive value of 97% (Table 1).
chapter
5
Table 1.
Studies of sentinel node biopsy with concommitant axillary dissection
in patients with breast cancer (from McMasters
et
al. [12])
Study No. of Pts with Tech- Sensi- Speci- Positive Negative Overall
SLN only False-
patients SLN nique tivity ficity predictive predictive accuracy
positive negative
identified
value value
node rate
no. (%)
(%) (%) (%)
(%)
(%) (%) (%)
All 1385 1198 (86) All 94 100 100
97
98
48
6.2
SLN, Sentinel lymph node.
