Relationship between tumor infiltrating lymphocytes and clinicopathological features in Peruvian gastric cancer

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Background: Role of tumor-infiltrating lymphocytes (TIL) over clinicopathological features including Mismatch Repair (MMR), HER2 status, Epstein Barr Virus (EBV) and Helicobacter pylori (HP) infection is not well understood in gastric cancer (GC). Methods: TIL level and HP infection was also evaluated in H&E from 503 Peruvian GC patients who underwent surgery. Density of CD3+ T cells, CD8+ cytotoxic T cells, CD163 M2 macrophages, as well as MMR and HER2 status were determined by immunohistochemistry. HP and EBV infection was also detected by qPCR in a 234 cases subset. Results: Median age was 62 years and 50.1% were female, most tumors were grade 3 (59.1%), intestinal subtype (44.8%) and stage III (59.8%). MMR loss was found in 29.4% and HER2+ in 4.7%. HP+ was detected by H&E in 55.7% and by qPCR in 63.7%. EBV+ by qPCR was found in 20.5% and co-infection along with HP in 9.4% (22/234). Stage (p < 0.001), intestinal histology (IH) (p = 0.019), grade (p = 0.006) and lymphovascular invasion (p < 0.001) were associated with longer survival. Median TIL was higher in invasive border (IB) and stromal (ST) than intratumoral (IT) compartment but there were significantly correlated (p < 0.001). High IT TIL was associated with absence of HP H&E (p = 0.009). High ST TIL was associated with older age (p < 0.001), IH (p < 0.001), grade 1 (p = 0.009), lower stage (p = 002), MMR loss (p = 0.019) and EBV+ (p = 0.001). Density of CD3 and CD8 were significantly correlated in IT and ST compartments (p < 0.001). High CD3 density in IT compartment was associated with grade 3 (p = 0.001) and HP- (p = 0.02), and in ST was associated with IH (p = 0.005), grade 1- 2 (p = 0.002) and MMR loss (p = 0.04). High IT CD8 was associated with HER2- (p = 0.016), HP- (p = 0.014) and EBV+ (p = 0.012). High ST CD8/CD3 ratio was associated with diffuse histology (p = 0.034), grade 3 (p = 0.013), more advanced stage (p = 0.022) and recurrence (p = 0.014). High ratio of IT CD8/CD3 was associated with MMR loss (p = 0.007). High ST TIL was associated with longer DFS (p = 0.007). Lower ratio of CD8/CD3 was associated with longer OS (p = 0.024) and DFS (p = 0.02). Conclusions: TIL levels and infiltrating immune subpopulations differs by clinicopathological features in GC including MMR loss, HER2 expression EBV and HP infection. ST CD8/CD3 was associated with recurrence and shorter DFS.

The relationship between tumour infiltrating lymphocytes, Epstein–Barr virus and Helicobacter pylori infection in gastric cancer

Objective

Epstein–Barr virus (EBV) and Helicobacter pylori (HP) infections have been extensively recognised as gastric cancer (GC) triggers, and recent publications suggest they could behave as predictive markers for immune-modulating therapies. Tumour-infiltrating lymphocytes (TILs) have also been identified as a predictive biomarker for immunotherapy in different malignancies. This study aimed to investigate the association between EBV and HP infection with TIL levels in GC.

Methods

TIL evaluation in haematoxylin-eosin was performed by a pathologist and density of CD3, CD8 and CD163 positive (immunohistochemistry staining) immune cells was calculated with the use of digital pathology software. EBV infection was detected by in situ hybridisation (ISH) and by quantitative polymerase chain reaction (qPCR). Methylation status of EBV-related genes was detected by PCR and a methylome analysis was performed by the Illumina Infinium MethylationEPIC BeadChip. HP status was detected by qPCR.

Results

We included 98 resected GC Peruvian cases in our evaluation. Median TIL percentage was 30. The proportion of EBV+ detected by ISH was 24.1%, of EBV+ detected by qPCR was 41.8%, while 70% showed methylation of EBV-related genes, and 58.21% of cases were HP+. Younger age (p = 0.024), early stages (p = 0.001), HP+ (p = 0.036) and low CD8 density (p = 0.046) were associated with longer overall survival (OS). High TIL level was associated with intestinal subtype (p < 0.001), with grade 2 (p < 0.001), with EBV qPCR+ (p = 0.001), and with methylation of EBV-related genes (p = 0.007). Cases with high TIL level and cases that are EBV positive share eight genes with similarly methylated status in the metabolomic analysis. High CD8 density was associated with EBV PCR+ (p = 0.012) and HP− (0.005).

Conclusion

Lower CD8 density and HP+ predict longer OS. High TIL level is associated with EBV+ and methylation of EBV-related genes, while lower CD8 density is associated with HP+ GC.

Prevalence of Helicobacter pylori Infection, Its Virulent Genotypes, and Epstein-Barr Virus in Peruvian Patients With Chronic Gastritis and Gastric Cancer

PURPOSE

Helicobacter pylori (HP) and Epstein Barr virus (EBV) infections induce chronic gastritis (CG) and are accepted carcinogenics of gastric cancer (GC). Our objective for this study was to determine the prevalence of these agents and clinicopathological features of GC and CG associated with the infection.

PATIENTS AND METHODS

A single-center cohort of 375 Peruvian patients with GC and 165 control subjects with CG were analyzed. Evaluation of HP and EBV genes was performed through quantitative polymerase chain reaction.

RESULTS

Prevalence of HP was 62.9% in the whole population and 60.8% in the GC subset. The cagA gene was detected in 79.9%; vacAs1 and vacAm1 alleles in 41.6% and 60.7%, respectively; and concurrent expression of vacAs1 and vacAm1 in 30.4% of infected patients in the whole series. The prevalence of EBV was 14.1% in the whole population and was higher in GC (P < .001). Coinfection of HP and EBV was found in 7.8% and was also higher in GC in univariate (P < .001) and multivariate (P = .011) analyses. Infection rates of HP and EBV were not associated with a geographic location in the whole series. Few clinicopathological features have been associated with infectious status.

CONCLUSION

Prevalence of HP infection and virulent strains are high in the Peruvian population. Infection by EBV was more frequent in patients with GC.