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10 Sentinel lymph node procedure
10.1 Summary of available scientific evidence LoE 1-
Diagnostic test accuracy according to the mapping method: three meta-analyses89-91 assessing the
diagnostic accuracy of SLN biopsy were identified. Hassanzade et al.89, Meads et al.90, and Lawrie et
al.91 included 47 studies92-138, 29 studies97,98,109,110,113-120,124-126,129,135,136,139-148, and 34 studies92,93,95,97-
,99,103,104,107,109,110,112,114-119,122-127,129,135,136,140-144,149-169 respectively. It should be noted that studies
included in these meta-analyses had methodological limitations, such as lack of an adequate
description of population (especially stage of disease), inclusion criteria, assessment procedure, and
reference standard used. Data from different reports of the same study were also taken into account.
Two meta-analyses89,90 reported pooled patient basis detection rate of various techniques and
provided evidence that a combination of blue dye/99mTc is the most accurate technique (Table 4). It
should to be noted that many of the studies taken into account by Meads et al.90 were also included
in the pooled analysis performed by Hassanzade et al.89, which explains the consistency of results.
Only Hassanzade et al.89 published pooled groin basis detection rate data and observed that it was
also higher with the use of the combined blue dye and 99mTc testing (Table 4).
Two of the three identified meta-analyses89,91 described per patient and per groin pooled sensitivity
of the SLN biopsy and provide evidence that a combination of blue dye/99mTc is also the most
sensitive technique (Table 4). It should to be noted that many of the studies taken into account by
Lawrie et al.91 were also included in the pooled analysis performed by Hassanzade et al.89, which
explains the consistency of results.
Diagnostic test accuracy according to the location of the tumour: Hassanzade et al.89 reported that LoE 1-
diagnostic test accuracy of the SLN procedure is also related to location of the tumour. For midline
lesions (≤ 2 cm of midline), per groin pooled detection rate was 22% lower than per patient pooled
detection rate but groin basis pooled sensitivity was 4% higher than patient basis pooled sensitivity
(Table 5). However, for lateral lesions (> 2 cm from the midline plane), per patient and per groin
pooled detection rates and sensitivity were similar.
Diagnostic test accuracy according to the tumour size: Hassanzade et al.89 observed that pooled LoE 1-
patient basis sensitivity was also related to the size of the primary tumour. Indeed, the pooled
sensitivity of SLN mapping in < 4 cm tumours was 7% higher than > 4 cm tumours (< 4 cm: 93%
(95% CI = 87-97), > 4 cm: 86% (95% CI = 77-93)). It should be noted that, in the Groningen
international study on sentinel nodes in vulvar cancer (GROINSS-V)170, sentinel-node detection was
done in patients with T1-T2 (< 4 cm) squamous-cell vulvar cancer.
Diagnostic test accuracy according to the inclusion of patients with palpable or suspicious inguinal LoE 1-
nodes in the study population: Hassanzade et al.89 observed that per patient and per groin pooled
patient basis detection rate and sensitivy were lower among patients with palpable or suspicious
inguinal nodes (Table 5).
Diagnostic accuracy of intraoperative pathologic analysis of frozen sections: as part of the LoE 2++
GROINSS-V170, frozen sectioning was done in 315 and showed a low sensitivity (48%) but a high
specificity (100%).
In contrast, two older and smaller studies (52 patients142 and 42 patients141) found sensitivity greater LoE 2+
than 90%. It should be noted that these two studies141,142 reported a specificity for intraoperative
analysis of SLN by frozen section greater than 90%. In the fourth identified study115, 18 positive
nodes were detected in 13 of the 43 enrolled women (30.2%). In two cases, although the frozen
section was negative, the definitive histopathologic examination revealed a micrometastasis
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