Techniques to increase lymph node harvest from gastrointestinal cancer specimens: a systematic review and meta-analysis

Aim: This review aims to compare different histopathological techniques for lymph node harvest from ex-vivo gastrointestinal cancer specimens and to examine their influence on: (i) lymph node yield; (ii) positive lymph node detection; and (iii) cancer staging. Method and results: Systematic review of the English language literature to 10 October 2011, comparing manual nodal dissection to other techniques for lymph node harvest. The methodological quality of included studies was assessed. Twenty-seven studies, examining fat clearing, methylene blue staining, fat stretching and use of a dedicated pathology assistant, were assessed. The methodological quality of the majority of included studies was poor. Meta-analysis showed that fat clearing and methylene blue staining increased mean lymph node yield by 13 and 15 nodes, respectively, when compared to manual dissection. Of the 15 studies reporting positive lymph node count, two demonstrated a significant improvement for techniques other than manual dissection. Compared to manual dissection, other techniques were not shown to influence cancer staging. Conclusion: This review has shown that fat clearing and methylene blue staining increases the mean lymph node yield from gastrointestinal cancer specimens. There is insufficient evidence to suggest that these techniques increase positive lymph node count or lead to upstaging.