The refrigerator may have helped cut stomach cancer in the West
Before the 1930s, stomach cancer was among the leading causes of cancer death in Western countries. Rates have since fallen sharply among younger Westerners, a decline often credited to refrigeration replacing salting and pickling as the way to keep food. In East Asia, where the disease remains common, screening has transformed survival.
Most stomach cancers are carcinomas that start in the stomach lining, usually developing in stages over many years. The bacterium Helicobacter pylori is linked to more than 60 percent of cases, though only about 2 percent of infected people ever develop the disease, and some strains carry more risk than others. Smoking raises risk by roughly 40 percent in current smokers and 82 percent in heavy smokers. Diets rich in salted, smoked or pickled food are associated with higher rates, although the evidence on individual foods is weak.
Heredity plays a smaller part. About 10 percent of cases cluster in families, and between 1 and 3 percent stem from inherited syndromes such as hereditary diffuse gastric cancer, caused by a mutation in the CDH1 gene on chromosome 16 that half of a carrier's children are likely to share. Men are affected twice as often as women, and the Epstein-Barr virus has been estimated to account for 84,000 cases a year.
Early disease is hard to spot. Heartburn, indigestion or upper abdominal pain can be the first signs, yet fewer than one in 50 people sent for endoscopy because of indigestion turn out to have cancer. By the time weight loss, vomiting or difficulty swallowing appear, the tumour has often spread to the liver, lungs, bones or lymph nodes. Confirmation requires a biopsy taken during endoscopy; in 2013 Chinese and Israeli researchers reported a pilot breath test designed to avoid that procedure.
Globally the cancer ranked fifth by number of cases and third by deaths, with 1.03 million new diagnoses and 783,000 deaths in 2018. Outcomes depend heavily on timing: caught early it can be cured, but in Western countries fewer than 10 percent of advanced cases survive five years. Five-year survival reaches 39.8 percent in the United States, over 65 percent in South Korea and over 70 percent in Japan, a gap attributed mostly to the two Asian countries' screening programmes.
Source: Stomach cancer
