Abstract
PurposeThe 8th edition of the American Joint Committee on Cancer (AJCC) tumor-lymph node-metastasis (TNM) staging system for gallbladder cancer (GBC) recommended that at least six lymph nodes (LNs) should be examined. But most patients with GBC had fewer than six LNs resected. This study aimed to establish an alternative index for assessing the LN status during the staging system for GBC patients with fewer than six LNs retrieved.Patients and MethodsPatient data was extracted from the Surveillance, Epidemiology, and End Results (SEER) database (cases between 2004 and 2013). X-tile software was used to determine the optimal cutoff value for lymph node ratio (LNR) and a concordance index (C-index) was used to evaluate the discriminatory powers of the two staging systems.ResultsThe majority of GBC patients in our cohort (1353, 78.5%) had fewer than six LNs examined. Among patients with inadequate LN examination, the higher number of LNs examined correlated with a lower proportion of patients. Using the TNM staging system, the C-index for patients with fewer than six LNs and patients with six or more LNs screened were 0.636 and 0.704, respectively. Using the staging system based on LNR (TNrM), the C-index for patients with fewer than six LNs retrieved and patients with six or more LNs retrieved were 0.649 and 0.694, respectively. Similar results were observed in patients with gallbladder adenocarcinoma (GBA).ConclusionTNrM might be superior to the 8th AJCC TNM staging system for stratifying GBC patients with fewer than six LNs examined, and it can complement TNM for more accurate risk stratification. Future prospective studies are needed to validate our findings.
Highlights
Gallbladder cancer (GBC) is a relatively rare but lethal malignancy of the biliary tract with a 5-year survival rate of less than 5% [1, 2]
The GBC patients are routinely stratified into different risk groups based on the American Joint Committee on Cancer (AJCC) tumor-lymph node-metastasis (TNM) classification
Skye et al showed that 28.2% of 2,955 GBC patients had more than one lymph nodes (LNs) retrieved based on the Surveillance, Epidemiology, and End Results (SEER) between 1991 and 2005 [6]
Summary
Gallbladder cancer (GBC) is a relatively rare but lethal malignancy of the biliary tract with a 5-year survival rate of less than 5% [1, 2]. The GBC patients are routinely stratified into different risk groups based on the American Joint Committee on Cancer (AJCC) tumor-lymph node-metastasis (TNM) classification. The 8th edition of the AJCC staging system that was updated in 2018 used an altered definition of N category based on the number rather than the anatomical location of metastatic lymph nodes (LNs) in the 7th edition [3, 4]. The AJCC cancer manual recommends examining at least six LNs. the number of LNs retrieved was usually less than 6 in most literatures. A multi-institutional study including 214 GBC patients reported that the median number of LNs examined was 4 [5]. There is an urgent need for an alternative index to accurately classify the LN status in case fewer than six LNs are retrieved
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