Abstract
ObjectiveThe purpose of this study was to explore the role of different undifferentiated components in the lymph node metastasis (LNM) of early mixed gastric cancer.MethodsA total of 1596 patients with EGC who underwent gastrectomy were divided into four types: pure differentiated (PD), pure poorly differentiated (Poorly D), pure signet ring cell carcinoma (SRC), and mixed. Mixed type was classified into four subtypes: differentiated-predominant type mixed with poorly differentiated component (MD-P), poorly differentiated-predominant type mixed with differentiated component (MP-D), differentiated-predominant type mixed with SRC component (MD-S), and poorly differentiated-predominant type mixed with SRC component (MP-S). We analyzed the clinicopathological differences between all types and the rates of LNM of patients fulfilling endoscopic submucosal dissection (ESD) criteria.ResultsLNM was more common in mixed (21.9%) than in PD (7.5%, P < 0.001) or SRC (11.3%, P < 0.001). When analyzed the subgroups of mixed type, LNM was more frequent in MD-P (15.4%) than in PD (7.5%, P = 0.003). LNM in MD-S (7.4%, P = 1.000) was not higher than in PD. MP-S (24.5%) showed a higher rate of LNM than SRC (11.3%, P < 0.001) rather than Poorly-D (22.7%, P = 0.681). For lesions satisfying ESD criteria, MD-S (0%, P = 1.000), and MD-P (5.9%, P = 0.12) did not have higher rates of LNM than PD (1.4%).ConclusionThe presence of poorly differentiated component but not SRC increases the LNM rate of mixed type. ESD is recommended for the treatment of MD-S and MD-P consistent with ESD criteria.
Highlights
We divided the mixed type (MD) type into differentiated-predominant type mixed with signet ring cell carcinoma (SRC) component (MD-S) and differentiated-predominant type mixed with poorly differentiated component (MD-P)
PD pure differentiated cancer, Poorly D poorly differentiated cancer, SRC signet ring cell cancer, MD-P differentiated-predominant mixed-type with poorly differentiated component accounted for less than 50%, MP-D poorly differentiated-predominant mixed-type with differentiated component accounted for less than 50%, MD-S differentiated-predominant mixed-type with signet ring cell component accounted for less than 50%, MP-S poorly differentiated-predominant mixed-type with signet ring cell component accounted for less than 50%
When compared with PD type, lymph node metastasis (LNM) was more common in the Mixed type (Mixed versus PD, 11.8% versus 1.4%, respectively, P < 0.001) and the SRC type (SRC versus PD, 7.9% versus 1.4%, respectively, P < 0.003)
Summary
A total of 1596 surgically treated patients with EGC treated in Renji Hospital, Medical College of Shanghai Jiao Tong University, between July 2008 and December 2018 were enrolled in this retrospective study. Patients with incomplete pathological information, multiple gastric cancers, other malignancies, and invasion deeper than the submucosa were excluded. These included age, gender, tumor size, location, macroscopic type, ulcer, depth of invasion, presence of LNM, N stage, and histology type. The χ2 test and multivariate analyses were performed to evaluate the effect of different mixed types on LNM. Multivariate analyses tested by logistic regression were used to compare groups. P < 0.05 was considered statistically significant. SPSS 23.0 for Windows was utilized for data analysis
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