Simultaneous gastric cancer in monozygotic twins.

Monozygotic twins developed gastric cancers that were found almost simultaneously. A 47-year-old man complained of nausea and vomiting; an upper gastrointestinal series and endoscopy revealed advanced gastric cancer invading the serosa. Palliative subtotal gastrectomy was performed. In his asymptomatic twin a gastric polyp was detected during a screening examination, and this was observed for 2 years. After the former twin had undergone surgery, the latter twin was given a detailed endoscopic examination, and biopsy revealed gastric cancer limited to within the mucosa. Curative subtotal gastrectomy was performed. The noncancerous gastric mucosa of the former twin showed severe intestinal metaplasia, but that in the latter showed only spotty metaplasia. They had lived together for 40 years, but the former was a heavy smoker and drank alcohol, while the latter did not. These differences in taste might have contributed to the observed difference in intestinal metaplasia, which indicates chronic mucosal damage.