Materials and Methods
Study Design and Participants.
A case-control design was used to investigate the association between tea consumption and ovarian cancer. Recruitment of cases focused on epithelial ovarian cancer that accounts for >90% of all of the ovarian malignancies (13) . Two hundred and fifty five hospital patients with epithelial carcinoma of the ovary were identified in Hangzhou, China, between July 1999 and June 2000. To ascertain cases, all of the relevant hospital and laboratory pathology reports were reviewed. Pathological diagnoses were based on the International Histological Classification of Ovarian Tumors recommended by the Fédération Internationale des Gynaecologistes et Obstetristes (13 , 14) . With the exception of 1 patient lost after discharge, all of the eligible cases were recruited during the period of data collection. Inclusion criteria for cases were defined to be women 500 beds and receive patients from all over the province. In 1999, there were ∼12,000 inpatients with 8,000 operations performed and 450,000 outpatients at the Women’s Hospital (15) . All of the hospitals are located in Hangzhou, the capital city of Zhejiang province. Most of the cases (75.2%) were recent patients interviewed within 12 months from diagnosis. Details of cases recruited are provided in Table 1⇓ .