Authors (including presenting author) :
SL Cheung, KF Wong, SK Leung
Affiliation :
Department of Surgery, Tuen Mun Hospital, Hong Kong
Introduction :
Lymph node staging is an essential component in cancer staging system including oesophageal cancer. Traditionally, we aimed to achieve an en-bloc resection of the diseased organ and sent to laboratory for histopathological examination. However, in the other side of the world, Japan, after the operation with en-bloc resection, Japanese surgeons will handle the operative specimen, harvest lymph nodes one by one and send the lymph nodes individually for histopathological examination. This practice is named Imohori (‘potato picking’ in Japanese) which provides a detail examination of the specimen and may increase the number of lymph node being harvested.
However, this practice is time-consuming and may need extra-manpower to handle the specimen. Therefore, a modified approach, Modified Imohori Practice (MIP), was adopted in our centre; aimed to increase lymph node harvesting but avoid a time-consuming procedure like the original Japanese imohori practice at the same time.
In Modified Imohori Practice (MIP), after en-bloc resection of the tumour, lymph node specimen were divided and sent for histopathological examination station by station according to the Japanese guideline instead of one lymph node by one lymph node. Identification of lymph nodes in specimen was mainly performed by pathologist in the laboratory. Theoretically, this simple change of practice can be time saving and at the same time improve the number of lymph node sampling, which in turns increase the accuracy of lymph node staging.
Objectives :
This study aims to reveal whether a modified approach, Modified Imohori Practice (MIP), in which lymph node specimen were divided and sent for histopathological examination station by station (lymph node stations are defined according to the Japanese guideline), could also help to improve the sampling rate of lymph node.
Methodology :
This is a single centre retrospective study. Patients who underwent oesophagectomy between 1/2011 and 6/2020 in a single centre i.e. Tuen Mun Hospital were identified. MIP was adopted since 2013. Patients were divided into non-MIP group (before using Modified Imohori Practice, 1/2011 – 12/2012) and MIP group (after adopting MIP, 1/2013 – 6/2020). Exclusion criteria include non-cancer patient, non-oesophageal origin cancer e.g. hypopharynx cancer, local recurrence, absence of lymph node dissection.
Patients’ clinical details were assessed via hospital electronic records. Factors, such as patients’ sex, age, procedures performed (e.g. laparoscopic assisted versus open), pathological information (e.g. tumour locations, disease staging, total number of lymph node harvested) were studied. The staging system applied is TNM staging AJCC UICC 8th edition in this study.
All statistical data was analysed by SPSS version 21. Categorical and continuous variables were compared by using Chi-square test (Fisher Exact test if appropriate) and Mann-Whitney-U Test respectively. Results were considered to be statistically significant if p-value was =< 0.05.
Result & Outcome :
Totally 90 patients were included. There were 23 patients (26%) in the Non-MIP group and 67 patients (74%) in MIP group. The MIP group is significantly older (mean age 64.9 vs 58.4, p-value 0.020) and has more lymph node harvested than the Non-MIP group (mean total number of lymph nodes harvested 37.4 vs. 25.9, p-value 0.004). There is no statistical significance about sex, type of operation, location of tumour, disease staging, tumour staging nor nodal staging between the groups.
This study shows MIP improves the sampling rate i.e. total number of lymph node. This may cause a stage migration effect and provide a more accurate staging for oesophageal cancer patients.
