Mixed-histologic-type submucosal invasive gastric cancer as a risk factor for lymph node metastasis: feasibility of endoscopic submucosal dissection.
OBJECTIVE
The clinicopathologic features of gastric cancers containing a mixture of differentiated-type and undifferentiated-type components remain uninvestigated. We evaluated the risk of lymph node metastasis and the feasibility of endoscopic submucosal dissection (ESD) for the treatment of mixed-histologic-type gastric cancers.


METHODS
We histologically classified 376 cases of gastric cancer with submucosal invasion into four types (differentiated type, differentiated-type-predominant mixed type, undifferentiated-type-predominant mixed type, and undifferentiated type) and studied the clinicopathologic relations of each type to lymph node metastasis. Lymphatic invasion was evaluated by D2-40 immunostaining.


RESULTS
The overall prevalence of lymph node metastasis in gastric cancer with submucosal invasion was 16.5% (62/376). The prevalence of lymph node metastasis was 36.5% (23/63) in undifferentiated-type-predominant mixed type, which was significantly higher than those in the other three types (P < 0.001 vs. differentiated type, P = 0.013 vs. differentiated-type-predominant mixed type, and P = 0.003 vs. undifferentiated type). Lymphatic invasion, a depth of invasion of 500 microm or more from the lower margin of the muscularis mucosae (SM2), tumor size above 30 mm, and undifferentiated-type-predominant mixed histologic type were independent risk factors for lymph node metastasis. Submucosal cancers without these four risk factors were free of lymph node metastasis (0/41; 95 % confidence interval 0%-8.6%).


CONCLUSIONS
Undifferentiated-type-predominant mixed-type gastric cancer with submucosal invasion carries a high risk of lymph node metastasis. ESD can be indicated for gastric cancer with submucosal invasion provided that the following conditions indicating a low risk of metastasis are met: a depth of invasion of no more than 500 microm or more from the lower margin of the muscularis mucosae (SM1), no lymphatic invasion, a tumor size of no more than 30 mm, and a proportion of undifferentiated components below 50%.
Hanaoka
N
N
Department of Gastroenterology, Kitasato University School of Medicine, Sagamihara-City, Kanagawa, Japan. noboley1121@aol.com
Tanabe
S
S
Mikami
T
T
Okayasu
I
I
Saigenji
K
K
D000230:Adenocarcinoma / Q000473:pathology* / Q000601:surgery*; D000231:Adenocarcinoma, Papillary / Q000473:pathology / Q000601:surgery; D000368:Aged; D018279:Carcinoma, Signet Ring Cell / Q000473:pathology / Q000601:surgery; D005240:Feasibility Studies; D005260:Female; D005753:Gastric Mucosa / Q000473:pathology* / Q000601:surgery*; D005773:Gastroscopy; D006801:Humans; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011379:Prognosis; D018570:Risk Assessment; D013274:Stomach Neoplasms / Q000473:pathology* / Q000601:surgery*; D047368:Tumor Burden