Methods / The Shanghai Cohort Study
Baseline Survey and Biospecimen Collection
This is a population-based prospective cohort study. The criteria for enrollment into the study were male residents of 45-64 years who resided within geographically defined four neighborhoods in the city of Shanghai, China. During January 1, 1986 through September 30, 1989, 18,244 men were recruited into the study. Approximately 80% of eligible men participated in the study. At the time of recruitment, each subject was interviewed in person by a trained nurse interviewer using a structured questionnaire that asked for information on demographics, education, body weight and height, type of occupation, history of smoking of cigarettes and other tobacco products, history of alcohol use, dietary intake, and medical history.
The cohort distributions of demographics are shown in table 6.
ii. Biospecimen collection
At the completion of the interview, the nurse collected a blood and a single void urine specimen from the study participant. All study participants provided both blood (10 mL) and urine (100 mL) samples. The collected biospecimens were kept in insulated boxes with ice (0-4oC) before they were processed in the study laboratory within 4 hours after the sample collection. Multiple vials of serum and urine samples per subject were created and stored at -72oC or below.
Mouthwash samples were collected from all surviving subjects beginning in 2000. By the end of 2001, Mouthwash samples were collected from 13,815 subjects.
The numbers of subjects who donated different types of biospecimen at baseline are shown in table 7.
Annual Follow-up Surveys
Follow-up surveys were performed by trained interviewers in person to all surviving subjects, first on an annual basis from 1990 to 2012, and biannually since 2013. The follow-up questionnaire collected information on any updates of subject’s residence in the coming year(s), interim health history including hospitalization (date, reason, name, medical record number), cancer diagnosis (site and subsite, histology, diagnosis criteria, and treatment for cancer), and other health outcomes and conditions, as well as the vital status of the study subject, if deceased, cause of death and diagnosis of the cause of death, date of death from subject’s next-of-kin. In addition, the follow-up questionnaire included questions on current smoking status and changes in smoking history during the past year, and consumption of alcohol and green tea. We also measured the subject’s blood pressure.
The cohort has been followed for the occurrence of cancer and death through routine ascertainment of new cases from the population-based Shanghai Cancer Registry and Shanghai Vital Statistics Units. We also conducted annual follow-up interviews to all known surviving subjects to minimize the loss of subjects from the study. As of the latest follow-up survey, 612 (3.4%) original subjects were cumulatively lost to follow-up (i.e., persons we have no record of death and we have been unable to locate through our annual follow-up recontacts), and 574 (3.1%) refused to our continued follow-up interviews (their cancer and vital status has been continually updated through record linkage analyses) after more than 25 years of follow-up since the beginning of the study.
i. Cancer Incidence
As of latest follow-up survey and record linkage analysis for the cohort participants with databases of the population-based Shanghai Cancer Registry, 4,371 (24%) of study participants developed cancer. The number of site-specific cancers are shown in table 8.
As of latest follow-up survey and record linkage analysis for the cohort participants with databases of the population-based Shanghai Vital Statistics Office, 9,158 (50.2%) study participants died. The number of major causes of death are shown in table 9.
Current Status of the Cohort
The cohort study originally recruited 18,244 men aged 45-64 years in 1986-1989. As of the latest follow-up, 9,158 subjects died, 754 subjects were lost to follow-up, and 597 were withdrawals from the study. Thus 7,735 study subjects were known to be alive and continued for follow-up interviews. The mean age on 12/31/2016 was 81 years (SD 5.4) with a range from 57 to 106 years (Figure 2).