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DOES HISTOLOGY REALLY INFLUENCE GASTRIC CANCER PROGNOSIS?
Carrie Luu*, Katherine Woo, Ram Thapa, Khaldoun Almhanna, Domenico Coppola, José M. Pimiento, Dung-Tsa Chen, Pamela J. Hodul
H. Lee Moffitt Cancer Center, Tampa, FL
Background: Gastric cancer (GC) is associated with poor survival despite curative-intent surgical resection and systemic therapy. Our objective is to examine the impact of histology on prognosis, which has been conflicting in previous reports. We also aim to evaluate the particular impact of linitis plastica (LP), a clinically infiltrative presentation of diffuse gastric cancer, on survival.
Methods: The gastric cancer database at a single institution was evaluated for patients who underwent resection from 2000 to 2015. Clinicopathologic characteristics were examined and descriptive statistics was used to analyze 4 groups of patients based on Lauren classification: intestinal (n=93), diffuse (n=20), diffuse with signet-ring cell features (n=57), and linitis plastica (n=40). Linitis plastica patients had diffuse GC but also presented with circumferential infiltration of the gastric wall for at least a third of the stomach length on endoscopy or imaging. Fisher's exact test was used to compare groups; Cox regression was used for multivariate analysis and Kaplan-Meier method for survival.
Results: Of 210 patients who underwent gastric resection, 112 (53%) were male with mean age 65.3 years (SD ± 14.6 years). Intestinal GC patients were older at diagnosis but other patient demographics were similar between all groups. Linitis plastica patients had a higher rate of R1 resection despite higher rates of total gastrectomy (p<0.01). Rates of perineural invasion (PNI) and nodal metastasis were higher in LP (p<0.001), as was lymphovascular invasion (LVI), though it was not significantly different between all groups. The majority of intestinal GC patients (79%) had stage I/II disease compared to 70% of LP patients who had stage III disease. Median overall survival (OS) was 1.1 years for linitis plastica, 6.6 years for intestinal , 8.1 years for signet-ring cell, and not reached for diffuse GC (p<0.001). When stratified by stage, there were no significant differences in survival by histology for stage II and stage III patients. However, by Cox regression analysis, factors associated with worse survival included lymphovascular invasion, nodal disease, and presence of linitis plastica. Lymph node ratio and neutrophil-lymphocyte ratio did not influence survival on multivariate analysis.
Conclusion: Intestinal gastric cancer is thought to have a better prognosis. Interestingly, this study demonstrates similar outcomes in patients with intestinal, diffuse, and signet-ring cell GC. However, a subset of diffuse gastric cancer-linitis plastica-was associated with an infiltrative pattern of disease characterized by PNI and LVI. Despite controlling for poor prognostic markers, linitis plastica was still associated with worse prognosis. More research is needed to identify methods of earlier diagnosis and effective systemic therapy to treat this aggressive disease.
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