Strengths and Limitations
This study has several strengths. First, a meticulous screening was
carried out to ensure that the data for analyzing did not contain any
reduplicative or ineligible individual. On the other hand, we had done
our best to re-analyze the existing data, collect unpublished studies
and contact the authors to obtain precise diagnostic information for
each included individual (supplementary p10–16). Each step of data
synthesis was detailed to make our results reproducible. Besides, most
of the included studies were prospective, used multiple tracers for SLNB
and ultrastaging for DPE, indicating low risk of bias in the results.
Furthermore, the L and E-protocol can be clearly distinguished and were
evenly used in previous studies, suggesting the
generalizability for both. In
addition, the studies in which FSE was selectively performed (usually
for SLNs with suggestive appearance) were excluded because there were
high risks of bias (supplementary). Finally, the sensitivity analyses
demonstrated the robustness of the main findings (supplementary).
This study also has several limitations. First, only nine studies
provided the sizes of TP and the question how many MIM/ITC were detected
under different protocols has not been satisfactorily answered.
Furthermore, due to the multidisciplinary nature of SLNB technique, the
sample size of single study was usually small. We could not eliminate
the impact of pathologists’ experience although all involved
institutions were highly specialized. This also poses a further question
whether our results can be validated in hospitals without enough
experience in SLNB. Besides, due to the length of time elapsed, some
authors could not be contacted or provide requested information,
including the diagnostic data, protocols of FSE and DPE, and the
metastatic types.