Gastric cancer, though present, is relatively low when compared to countries with high incidence like Japan and China. One suspected cause of the variation within Africa and between other countries is due to different strains of the H. pylori bacteria. The trend commonly seen is that H. pylori infection increases the risk for gastric cancer, but this is not the case in Africa, giving this phenomenon the name the "African enigma". Although this bacterial species is found in Africa, evidence has supported that different strains with mutations in the bacterial genotype may contribute to the difference in cancer development between African countries and others outside the continent. Increasing access to health care and treatment measures have been commonly associated with the rising incidence, though, particularly in Uganda. Other animals
The stomach is a muscular organ of the gastrointestinal tract that holds food and begins the digestive process by secreting gastric juice. The most common cancers of the stomach are adenocarcinomas, but other histological types have been reported. Signs vary, but may include vomiting (especially if blood is present), weight loss, anemia, and lack of appetite. Bowel movements may be dark and tarry in nature. To determine whether cancer is present in the stomach, special X-rays and/or abdominal ultrasounds may be performed. Gastroscopy, a test using an endoscope to examine the stomach, is a useful diagnostic tool that can also take samples of the suspected mass for histopathological analysis to confirm or rule out cancer. The most definitive method of cancer diagnosis is through open surgical biopsy.
In particular, HER2 is overexpressed in 13–22% of patients with gastric cancer. Of note, HER2 overexpression in gastric neoplasia is heterogeneous and comprises a minority of tumor cells (less than 10% of gastric cancers overexpress HER2 in more than 5% of tumor cells). Hence, this heterogeneous expression should be taken into account for HER2 testing, particularly in small samples such as biopsies, requiring the evaluation of more than one bioptic sample. Radiation
Radiation therapy (also called radiotherapy) may be used to treat stomach cancer, often as an adjuvant to chemotherapy and/or surgery. Lymphoma
MALT lymphomas can often be fully treated by treating an underlying H. pylori infection. This results in remission in about 80% of cases. Prognosis
The prognosis of stomach cancer is generally poor, because the tumor has often metastasized by the time of discovery, and most people with the condition are elderly (median age is between 70 and 75 years) at presentation. The average life expectancy after being diagnosed is around 24 months, and the five-year survival rate for stomach cancer is less than 10%.Almost 300 genes are related to outcomes in stomach cancer, with both unfavorable genes where high expression is related to poor survival and favorable genes where high expression is associated with longer survival times. Examples of poor prognosis genes include ITGAV, DUSP1 and P2RX7. Epidemiology
Worldwide, stomach cancer is the fifth most-common cancer with 952,000 cases diagnosed in 2012. It is more common both in men and in developing countries.