Page 13 - Helicobacter pylori and Gastric Cancer: From Tumor microenvironment to Immunotherapy

Gastric cancer
Gastric cancer remains a significant public health problem globally, and it is among the leading causes of cancer-associated mortality world-wide(5, 6). Although only 25–30% of gastric cancer patients will survive the five years following diagnosis, substantial heterogeneity of survival rates is reported in clinical trials, and this may relate to variations in the biological and genomic make-up, especially when Western and Asian populations are compared(7). Gastric cancer incidence dramatically varies across different geographical areas, being the highest in Japan, China, Far Eastern countries, Russia, Middle Eastern area, and in the Pacific coast of the South American continent and the being the lowest in Central Africa. Europe and North American regions share an intermediate-to-high incidence(8). Stomach and breast cancers have the highest incidence rates of all other cancers and are for instance among the most common causes of death in Iran(8). Conversely; there are low prevalence and incidence rates in sub-Sahara Africa(9-13). Gastric cancer patient’s prognosis is a function of disease stage progression, in which less than 20% progress to advanced stages in patients surviving five years following diagnosis. It appears important to individualize treatment and screening strategies for the high-risk groups. Several risk factors are responsible for the progression to advanced stages of gastric cancer(14-17). Gastric cancer risk is associated with Helicobacter pylori infection which accounts for 70% cancer incidence in the stomach, and accordingly, the eradication of this bacteria provides primary prevention for cancer development(2, 18). Generally, one can say that family history, intestinal metaplasia, salt intake, smoking, alcohol and H pylori infection are the most significant risk factors for developing the premalignant conditions that ultimately give rise to gastric cancer development(19-22). Japan and South Korea adopted a strategy of early detection among other approaches, which has resulted in a favorable decrease in incidence and prevalence rate. The median survival rate of full-blown gastric cancer is only 9 to 10 months. There is hope that profiling of immune and molecular details of the disease, as well as the introduction of immune checkpoints inhibitors, may increase the overall survival rate and the present thesis also aims to contribute in this respect.
Chapter 1
General introduction
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