Juniper Publishers: Sentinel Lymph Node Mapping in Gynecological Malignancies-Are We Ready for Routine Clinical Use?
JUNIPER PUBLISHERS- JOURNAL OF GYNECOLOGY AND WOMEN’S
HEALTH
Journal of Gynecology and Women’s Health-Juniper
Publishers
Authored by Neelam Aggarwal*
Abstract
Sentinel lymph node mapping over a period of time has
gained popularity in gynecological cancers In case of vulvar and
cervical cancers results are quite convincing. Combined mapping methods
along with ultrastaging and immunohistochemistry of sentinel nodes has
shown higher detection rate with negligible false negative results. But,
still to validate the place of sentinel lymph node mapping in
management of gynecological cancers more multicentric studies are
required.
Keywords: Sentinel lymph node; Gynecological cancers; ImmunohistochemistryBackground
Lymphatic metastasis is one of the commonest routes
of spreading of gynecological malignancies and therefore, no doubt that
the status of lymph nodes has got vital role in the management and
planning of these tumours. The first lymph node draining the lymphatic
flow with the highest possibility of involvement is called sentinel
lymph node (SLN). In accord with lymphatic mapping hypothesis, it is
likely that negative sentinel lymph node biopsy rules out the
probability of involvement of non-sentinel nodes, however there is
possibility of false results as cited in literature [1].
Role of sentinel lymph node mapping concerning vulvar & cervical
cancer has place in the current American & European guidelines,
whereas in case of endometrial cancer it is still investigational. The
purpose of index article is to review & discuss the state of art of
sentinel lymph node mapping & its various approaches in
gynecological malignancies. The search strategy for this included
relevant articles related to SLN biopsy, their cross references,
keywords and meta-analysis published.
Mapping Methods
Sentinel lymph node mapping is done by various
techniques like dye labeling, use of radioactive substance or combined
modality. Inert vital dye, Isosulphan blue is injected at the junction
of tumour and healthy tissue in case of vulvar cancer and in peritumoral
cervical stroma circumferentially with median staining time of 20
minutes [2,3].
Another technique of mapping with radioactive substance involves
peritumoral injection of Technetium -99 (Tc-99) labelled colloids such
as Sulphur, Carbon or Albumin. Sulphur colloids are injected 2-4 hours
prior, while albumin labelled ones are used one day prior to surgery.
Identification of SLN is done usually with gamma probes. First draining
lymphatics are located in groin in case of vulvar cancer while in
cervical and endometrial cancer they are deep around iliac vessels,
sometimes with complex anatomy. Therefore, preoperative use of single
photon emission tomography/computed tomography (SPECT/CT) or intra
operative portable gamma camera can guide the surgeon during the surgery
in cervical or endometrial cancers. Other recent advances like hybrid
tracers and 3-D navigation devices may represent complementary tools by
improving the intra operative visualization of sentinel lymph nodes.
Sentinel lymph node biopsy in vulvar cancer
Vulvar cancer accounts for 3-5% of gynecological malignancies [4].
As the pattern of dissemination in vulvar cancer is lymphogenic,
therefore the lymph node metastasis represents the most important
prognostic factor. Standard treatment of vulvar cancer includes radical
vulvectomy and inguinofemoral lymphadenectomy, however only a third of
patients in early stage will have lymph node involvement. So a standard
protocol of elective inguinofemoral lymphadenectomy in patients with
early stages may not benefit all, but risking significant morbidity in
terms of wound infection and breakdown, lymphedema and cellulitis [5-9].
So, accurate identification of sentinel lymph node in early stage
vulvar cancer may potentially spare the patients from common morbidities
of the inguinofemoral lymphadenectomy (IFL) but on the other hand
unrecognized disease in the lymph nodes may prove fatal. The sentinel
lymph node obtained by injecting blue dye or /and using radiolabeled
colloid is histologically examined (ultra staging) and also subjected to
immunohistochemistry (IHC).
In a meta-analysis of 29 studies (1779 women), SLN
detection rate was 68.7% with blue dye, 94% for Tc-99 and highest up to
97.7% with combined mapping method. Pooled sensitivity upto 95% with
negative predictive value of 97.9% were seen in studiesusing 99mTc/blue
dye, ultrastaging and immuno histochemistry with IFL as reference. No
doubt, patients undergoing SLN biopsy experienced less morbidity than
thosewho had IFL. So they concluded that sentinel lymph node biopsy with
combined mapping method (dye+Tc 99) along with ultra staging and IHC is
highly accurate in properly selected patients and they should be
followed cautiously [10].
Furthermore omission of IFL where sentinel lymph node is negative may
be better understood after the results of on-going multicenter studies
(GOG-0270 and GROINSS V11).
Sentinel lymph node biopsy in cervical cancer
Cervical cancer is the commonest gynecological cancer
of the developing countries & like vulvar cancer lymph node
metastasis is the most important factor for recurrence and mortality. A
number of studies have been carried out in an attempt to investigate the
usefulness of SLN biopsy in cervical cancer. Pooled sensitivity of 80%
with methylene blue and up to 92% with Tc-99 has been reported in
literature. Detection rate of up to 97% has been found with combined
methods [11,12].
A study by Roca et al has shown very high negative predictive of
sentinel lymph node biopsy in early stage cervical cancer & strongly
recommend the incorporation of this simple technique in the routine
clinical use [13].
Some authors has advocated the usefulness of this technique in only
cervical tumors of less than 2 cm with common histological subtypes [14,15].
Sentinel lymph node mapping in selective group of patients combined
with accurate intra operative histological assessment could reduce
surgical related morbidity in patients of early stage cervical cancer [16-18].
Sentinel lymph node biopsy in endometrial cancer
Increased rate of complications because of extensive
lymph node dissection to stage patient's disease inendometrial cancer
has led to concept of sentinel lymph node mapping. Out of described
mapping techniques, hysteroscopic injection has shown good results in
endometrial cancers. Because of technique difficulties to assess the
injection area due to the complexity of lymphatic drainage in
endometrial cancer limited studies of sentinel lymph node mapping are
available.
Conclusion
No doubt, over a period of few years multiple studies
on sentinel lymph node mapping has shown promising results, still there
are few aspects that needs to be emphasized .Incorporation of new
technical modalities to improve detection rate, ultra staging along with
immunohistochemistry of sentinel nodes and innovative management
approaches need to be developed .Furthermore prospective multicentric
studies are required to validate the place of sentinel lymph node
mapping in management of gynecological cancers.
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