Prognostic value of diffuse versus intestinal histotype in patients with gastric cancer : a systematic review and meta-analysis

Background: There are two distinct types of gastric carcinoma (GC), intestinal, more frequently sporadic and linked to environmental factors, and diffuse (undifferentiated) that is highly metastatic and characterized by rapid disease progression and a poor prognosis. However, there are many conflicting data in the literature concerning the association between histology and prognosis in GC. This meta-analysis was performed to provide demonstration if histology according to Lauren classification is associated with different prognosis in patients with GC. Methods: We searched PubMed, the Cochrane Library, SCOPUS, Web of Science, CINAHL, and EMBASE for all eligible studies. The combined hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) in terms of overall survival (OS) were evaluated. Results: A total of 73 published studies including 61,468 patients with GC were included in this meta-analysis. Our analysis indicates that GC patients with diffuse-type histology have a worst prognosis than those with intestinal subgroup in all studies (HR 1.23; 95% CI, 1.17-1.29; P < 0.0001), in both loco-regional confined (HR 1.21; 95% CI, 1.12-1.30; P < 0.0001) and advanced disease (HR 1.25; 95% CI, 1.046-1.50; P=0.014), in Asiatic (HR 1.2; 95% CI, 1.14-1.27; P < 0.0001) and Western patients (HR 1.3; 95% CI, 1.19-1.41; P < 0.0001), and in those not exposed (HR 1.15; 95% CI, 1.07-1.24; P < 0.0001) or exposed (HR 1.27; 95% CI, 1.17-1.37; P < 0.0001) to (neo)adjuvant therapy. Conclusions: Our results indicated that histology might be a useful prognostic marker for both early and advanced GC patients, with intestinal-type associated with a better outcome. This information could be used for stratification purpose in future clinical trials.