Observations on gastric cancer in San Marino. I. Familial factors.

The Republic of San Marino (RSM) is a 23-square mile independent country within Italy with a population of 20,000. A large percentage of deaths have been found to be due to gastic cancer (9.2% of all death certificate diagnoses for 1969 through 1973). The frequency of gastric cancer in the families of all 36 patients (78% male) who were born and died in RSM with this diagnosis for this period was compared with the frequency in relatives of age and sex-matched controls. Although 42--44% of both groups had relatives with death certificate diagnoses of stomach cancer, 25% of the patients had first degree relatives affected versus 5.6% of the controls. A high prevalence has also been reported in the area of Italy near RSM. San Marino's size and stability of population provide unique opportunities for elucidating genetic and environmental etiological factors in stomach cancer.