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BACKGROUND: The Sister Study was designed to address gaps in the study of environment and breast cancer by taking advantage of more frequent breast cancer diagnoses among women with a sister history of breast cancer and the presumed enrichment of shared environmental and genetic exposures. OBJECTIVE: The Sister Study sought a large cohort of women never diagnosed with breast cancer but who had a sister (full or half) diagnosed with breast cancer. METHODS: A multifaceted national effort employed novel strategies to recruit a diverse cohort, and collected biological and environmental samples and extensive data on potential breast cancer risk factors. RESULTS: The Sister Study enrolled 50,884 U.S. and Puerto Rican women 35-74 y of age (median 56 y). Although the majority were non-Hispanic white, well educated, and economically well off, substantial numbers of harder-to-recruit women also enrolled (race/ethnicity other than non-Hispanic white: 16%; no college degree: 35%; household income <$50,000: 26%). Although all had a biologic sister with breast cancer, 16.5% had average or lower risk of breast cancer according to the Breast Cancer Risk Assessment Tool (Gail score). Most were postmenopausal (66%), parous with a first full-term pregnancy <30 y of age (79%), never-smokers (56%) with body mass indexes (BMIs) of <29:9 kg=m² (70%). Few (5%) reported any cancer prior to enrollment. CONCLUSIONS: The Sister Study is a unique cohort designed to efficiently study environmental and genetic risk factors for breast cancer. Extensive exposure data over the life-course and baseline specimens provide important opportunities for studying breast cancer and other health outcomes in women. Collaborations are welcome. [ABSTRACT FROM AUTHOR]

Objective: We aimed to assess the relative validity and reproducibility of a semi-quantitative FFQ in Puerto Rican adults.Design: Participants completed an FFQ, followed by a 6 d food record and a second administration of the FFQ, 30 d later. All nutrients were log transformed and adjusted for energy intake. Statistical analyses included correlations, paired t tests, cross-classification and Bland-Altman plots.Setting: Medical Sciences Campus, University of Puerto Rico.Subjects: Convenience sample of students, employees and faculty members (n 100, ≥21 years). Data were collected in 2010.Results: A total of ninety-two participants completed the study. Most were young overweight females. All nutrients were significantly correlated between the two FFQ, with an average correlation of 0·61 (range 0·43-0·73) and an average difference of 4·8 % between them. Most energy-adjusted nutrients showed significant correlations between the FFQ and food record, which improved with de-attenuation and averaged 0·38 (range 0·11-0·63). The lowest non-significant correlations (≤0·20) were for trans-fat, n 3 fatty acids, thiamin and vitamin E. Intakes assessed by the FFQ were higher than those from the food record by a mean of 19 % (range 4-44 %). Bland-Altman plots showed that there was a systematic trend towards higher estimates with the FFQ, particularly for energy, carbohydrate and Ca. Most participants were correctly classified into the same or adjacent quintile (average 66 %) by both methods with only 3 % gross misclassification.Conclusions: This semi-quantitative FFQ is a tool that offers relatively valid and reproducible estimates of energy and certain nutrients in this group of mostly female Puerto Ricans. [ABSTRACT FROM AUTHOR]