OBJECTIVETo study the time trends during 1973 - 2004 and the current characteristics of gastric cancer incidence in Shanghai and to develop strategies for control and prevention.

METHODSAll data from the Malignant Cancer Registry System of Shanghai were retrieved and time trends of male and female incidence rates for gastric cancer in urban population from 1973 to 2004 were assessed by annual percentage change (APC) of the crude rates and age-adjusted rates. The APC was calculated by fitting a least squares regression line to the natural logarithm of the rates, using the calendar year as a regressor variable. Based on the computerized data from 2002 to 2004, the current characteristics of urban gastric cancer incidence were analyzed regarding sex, age, stage at diagonsis, histopathologic type and location of the tumor (s). The number and structure of population were obtained from Shanghai Municipal Public Security Bureau. The incidence rates were standardized under the world population. The constituent ratios were analyzed by Chi-square test. Statistical analyses were performed with the SPSS software package for Windows, version 10.0.

RESULTSSubstantially and continuously decreasing trends were noticed in gastric cancer incidence during the past 32 years in urban Shanghai, both in males and in females. The age-standardized rates (ASR) dropped 54.4% in males and 37.6% in females. From 2002 to 2004, 7630 new cases of gastric cancer were registered in urban Shanghai with the ASRs of male and female gastric cancer as 27.4 and 14.0 per 100 000. Under the age of 40, the age-specific incidence was quite low that no differences were found between men and women. However, the incidence increased significantly after age of 40 and differences of increase were shown between the two sexes. About 46.1% of all the cases had detailed records of TNM stage, in which IV stage was the majority while I stage the least. About 74.1% of all the cases were diagnosed histopathologically and 71.7% of all had detailed records on histopathologic types. Adenocarcinoma was the most common type (76.8%), followed by signet ring cell carcinoma (9.4%). The proportions of adenocarcinoma and tubular adenocarcinoma were higher in males than in females while signet ring cell cancer was higher in females than in males. Intestinal type gastric cancer was the most prominent type in Lauren system. The proportion of male was higher than female in intestinal type whereas female was higher than male in diffused type. In lesion location, the antrum was the most common tumor site. The gastric antrum cancer of females was more common than males while the gastric cardia cancer presented quite the contrary. The proximal gastric cancer was more prevalent in males than in females whereas the distal gastric cancer was in opposite pattern.

CONCLUSIONA dramatic decreasing trend during 1973 - 2004 and several current and interesting characteristics in view of gender, age, stage at diagnosis, histopathologic type and tumor location of gastric cancer in urban Shanghai were determined in this study, which might contribute to the development of control and prevention strategy for gastric cancer.