| Gastric cancer (GC) is one kind of the most common malignant cancers in the world. The mortality rate of GC lists the second in the global mortality rate of malignant cancers. In China, it is also one of the most common malignant cancers, it lists the top mortality rate of all malignant cancers, the average mortality rate is 16 per 100,000, in some areas, it reaches 60 per 100,000. Japan has the highest incidence of gastric cancer in the world, followed by Chile, Costarica and Hungary. The incidences of gastric cancer in Africa, North America countries, India, Indonesia are lower. Nowadays, there are approximately 800,000 new cases each year worldwide. In some developing countries, gastric cancer is the first malignant cancer in male, and the third in female. People usually get gastric cancer at 40 to 60 years old, the average age is 50, only 5% of the patients under the age 30. According to sex, the incidence of gastric cancer in male two times than that in female globally, and it is near 3~4 times higher in male in China.Gastric cancer is usually caused by multiple risk factors. There are many risk factors such as Helicobacter pylori infection, genetic polymorphism, dietary habit, smoking, psychological factors and so on. There have been many epidemiological studies about the cause of gastric cancer, but the reports were different.Jiashan county is located in Zhejiang province, it has 506.6 square kilometers, the population is 380,000. Take 2003 as an example, there were 860 cases of malignant cancers, 128 cases of them were gastric cancers, 680 persons died in cancer, about24.59% of all death cases. Meanwhile, Jiashan county has established an effective registering system for cancer, the foundation of prevention and control for cancer is good.In our study base, a cross-sectional survey about living situation of local people was conducted in 1989. Using the data collected in this survey, we organized a cohort study from May 1, 1990 to December 31, 2003. This paper focused on four main factors: smoking, alcohol drinking, different types of drinking water and fresh vegetables intake. Cox regression was used to analyze these factors of gastric cancer, we hope to prove the relationship and tension between those risk factors and gastric cancer, and to provide scientific evidence for the etiology of gastric cancer.Material and MethodsIn 1989, we surveyed 75842 persons over the age 30 in 10 villages and towns, the content of questionnaire including: general situation, such as age, sex, job, education, marriage; living habits, such as diet, drinking water, smoking, alcohol drinking; some symptoms and disease history associated with gastric cancer, such as abdomen surgery history, family history of cancers, mental illness history and so on. We received 64693 valuable questionnaires, the response rate was 85.3%.The information about new cases of gastric cancer was provided by the Control and Prevention Institute of Cancer in Jiashan annually. The institute also provided the detailed information about death cases. The period of observation was from May 1, 1990 to December 31, 2003.Censored data include cases who died in other reasons, cases who lost to follow-up or cases who did not get gastric cancer during the observation period. As for the ending time of observation, cancer patient refers to the time of diagnosis, death case refers to death time, other person means the time when observation was ended. One day was regarded as an observation unit, from the beginning time (May 1, 1990) to the ending time of observation, we calculated the time by datedif () function in Excel software, and analyzed the risk factors by Cox regression.Results1. General situation of gastric cancerThe incidence of gastric cancer counted on person-years showed that the incidences of gastric cancer in both male and female increased with age growing (P<0.05). The average incidence in male was 76.83/100 000 person-years while in female was 31.20/100 000 person-years. Among all 454 gastric cancer cases, the youngest was 30 while the oldest was 81, mean... |
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