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± 94.2%). NPV were available in 13 studies reaching values by the lymphatic system may vary and are dependent on
between 88% and 100% (mean ± 94.4%). the size of the particles. Small particles are drained and
cleared first; large particles are drained and cleared last
In only 5 works, the survival data were displayed in terms and may be retained longer at the injection site. There
of DFS, OS and DSS regard the SLNB results. These 5 works is worldwide variation in radiopharmaceuticals used for
showed the data detailing the positivity or negativity of the lymphoscintigraphy. Tc-99m sulphur colloid is employed in
nodes biopsied. In only 2 studies the terms of survival were the USA, with an average size ranging from 305 nm to 340
also displayed depending of the type of node invasion, isolated nm and Tc-99m-nanocolloid are used in Europe with size
[30]
tumoral cells (ITC), micrometastases or macrometastases. [24,26] All ranging from 5 nm to 100 nm. Studies have shown that
type of node invasion showed significant differences in terms of the success rate of identification of SNs is not significantly
DFS, OS and DSS respect to the absence of node invasion. The affected by the particle size of the radiotracer. [31-34] Thus, the
two works were published by Broglie et al. [24,26] in 2011 and 2013 selection of radiotracer is based more on local availability
obtaining very similar values for DFS for the pathological results than on differences in sentinel lymph node (SLN) detection.
of SNB negative, ITC, micrometastases and macrometastases.
Those results were: 96% and 98%, 80% and 75%, 69% and 71%, Recent developments in new tracers are coming, like the use
62% and 67%, respectively. The values obtained for OS for the of indocyanine green-Tc99m-nanocolloid, a hybrid tracer that is
same pathological results were: 88% and 98%, 80% and 89%, 75% both radioactive and fluorescent. The addition of fluorescence
and 71%, 62% and 67%, respectively. Finally, the values obtained imaging was shown to be of particular value when SNs were
for DSS for those pathological results were: 96% and 95%, 80% located in close proximity to the primary tumour. [35]
and 75%, 75% and 66%, 73% and 65%, respectively [Table 2].
©
Tilmanocept , is another novel receptor-targeted radio-
DISCUSSION pharmaceutical, Tc99m-labeled non-particulate radiotracer with
high affinity for the macrophages and dendritic cells, within
SNB is a well contrasted technique for the regional the sentinel lymph node. Studies have been promising, with
evaluation of tumor staging in breast cancer and melanoma suggestions that tilmanocept may have improved clearance
included in international guidelines of management of from the site of the primary tumor and enhanced retention
these tumors. [10,11] However, in OSCC it still remains with within the sentinel node when compared to sulfur colloid. [36]
an investigational role. This procedure is very complicated
in head and neck tumors because of the great wealth Based upon the experience accumulated in SNLB in other
of lymphatic vessels and a great variability of regional tumors, consensus on the activity to be administered in a
lymphatic migration. We selected articles published in the SNB procedure has not been reached. The investigated and
last 5 years, as accumulated experience has induced some suggested activities vary considerably. Activities as low as
[37]
[36]
evolution in radioisotope procedures, imaging techniques 3.7 MBq (0.1 mCi) and as high as 370 MBq (10 mCi) have
and radio-surgery procedures. We included 2 interesting been used. In our review, the doses ranged between 10 and
prospective papers published in 2002 and 2004 because 80 MBq, the adequate dose if the tracer administration is
they reach every required criteria, with high number of performed the day before surgery, especially if we are going
patients and included detailed data of survival respect to to acquire SPECT-CT images that require greater tracer
the histological findings of IHC. [27,28] activity. These doses do not imply a significant radiation dose
to the workers in the operation room. Note that between
We selected only prospective studies because they imply an administration of the radiotracer and surgery usually pass at
approach and prior review of the different techniques used. In least 24 h. It means that an administered dose will become
OSCC, the first studies have only been published since 1999, to 1/16 of the injected at the operation time, so that no
7 years after the technique gained acceptance in breast and specific radioprotection precautions are required.
melanoma. This, combined with the reduced incidence of oral
cancers compared to melanoma and breast cancer, necessarily Radiotracer administration
[25]
results in a low number of studies with more than 30 patients, Respect to the volume of radiotracer injected, Chone et al.
but it is similar to some meta-analysis reviewed. [29] employed the largest volume per dose (0.5 mL) in an attempt
to completely surround the tumor in its deep and lateral
Radiotracer aspects at a sub-mucous level of normal mucous membrane
Seven studies employed Tc99m-nanocolloid as radiotracer that surrounds the tumor in a volume of approximately
and 6 used Tc99m-sulphur colloid [Table 1]. Values of SS 1-2 mL. However, we did not find any significant difference
and NPV ranged between 88-100% and 86-100% with Tc99m- in terms of SS or NPV. In breast cancer with peritumoral
nanocolloid, and between 80-95% and 93-98% with sulphur injections, larger volumes per dose (i.e. 0.5-1.0 mL) are
[33]
colloid. The number of studies is very low but there were preferred for the same reason. Perhaps the best option
no significant differences. would be to try the peritumoral region completely
surrounded by the radiotracer to avoid false negative results.
Several 99mTc-based agents have been used for radioguided
SNB. The ideal radiotracer should show rapid transit to SN preoperative localization
SNs with prolonged retention in the nodes. In general, the The most common method to preoperatively localize
drainage, distribution, and clearance of radioactive colloids SN included injecting a radioactive sentinel node tracer
146 Plast Aesthet Res || Volume 3 || May 25, 2016