We used the same procedures in the NJ Ovarian Cancer Study and the EDGE Study to standardize data collection in cases and controls. Interviewers were trained using the same procedures and same training manual. Interviews, conducted by telephone for most respondents, covered established and suspected risk factors for ovarian cancer. In addition to the interview, participants were mailed a package with instructions for providing buccal specimens and waist and hip circumference measurements and the Block 98.2 food frequency questionnaire (FFQ). Participants were instructed to report their usual intake of the food items in the questionnaire during the six months before diagnosis (for cases) or the date of the interview (for controls). Two hundred and five (88%) cases and 398 controls (85%) returned the FFQ. The participants who returned the FFQ tended to be older, but there were no significant differences in education, oral contraceptive use, hormone replacement therapy use, tubal ligation or family history of ovarian cancer (data not shown). Eight of the controls were excluded because both of their ovaries had been removed, placing them at negligible risk of developing ovarian cancer, resulting in 390 controls being included in analyses.
The Block 98.2 FFQ (NutritionQuest, Berkeley, CA) includes 110 food items and was developed using the NHANES (National Health and Nutrition Examination Survey) III dietary recall data. It also includes questions on portion size for each food, and pictures are provided to facilitate estimation. The questionnaire includes a variety of foods containing phytoestrogens, such as several kinds of beans, tofu, soymilk, canned tuna fish, meat substitutes (e.g., veggie burgers, veggie chicken), and whole wheat bread. To supplement the list of foods, we added one page with 21 additional food items, based on the LACE questionnaire [28 (link)] and including other food items that have been identified as important sources of phytoestrogens [29 (link)]. The additional foods in the supplemental page that we added, and that are not included in the Block 98.2 questionnaire, are listed in Appendix 1. We also asked about the use of phytoestrogen/soy supplements including frequency and duration of use. NutritionQuest provided nutrient calculations using the USDA Nutrient Database for Standard Reference. For phytoestrogen calculations we used a Canadian database with detailed analyses of phytoestrogen content of foods, including detailed values for lignans [23 (link)]. Given the global food trading, we do not expect major differences in lignan composition between foods available in the United States and Canada.
The Block 98.2 FFQ (NutritionQuest, Berkeley, CA) includes 110 food items and was developed using the NHANES (National Health and Nutrition Examination Survey) III dietary recall data. It also includes questions on portion size for each food, and pictures are provided to facilitate estimation. The questionnaire includes a variety of foods containing phytoestrogens, such as several kinds of beans, tofu, soymilk, canned tuna fish, meat substitutes (e.g., veggie burgers, veggie chicken), and whole wheat bread. To supplement the list of foods, we added one page with 21 additional food items, based on the LACE questionnaire [28 (link)] and including other food items that have been identified as important sources of phytoestrogens [29 (link)]. The additional foods in the supplemental page that we added, and that are not included in the Block 98.2 questionnaire, are listed in Appendix 1. We also asked about the use of phytoestrogen/soy supplements including frequency and duration of use. NutritionQuest provided nutrient calculations using the USDA Nutrient Database for Standard Reference. For phytoestrogen calculations we used a Canadian database with detailed analyses of phytoestrogen content of foods, including detailed values for lignans [23 (link)]. Given the global food trading, we do not expect major differences in lignan composition between foods available in the United States and Canada.
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