THE ASSOCIATION BETWEEN CRUCIFEROUS VEGETABLES INTAKE AND BREAST CANCER RISK AMONG WOMEN WITH FAMILIAL BREAST CANCER by Lai Jiang A master thesis submitted to Johns Hopkins University in conformity with the requirements for the degree of Master of Science in Cancer Epidemiology, Department of Epidemiology at Johns Hopkins Bloomberg School of Public Health Baltimore, Maryland April 21, 2016 © 2016 Lai Jiang All Rights Reserved ABSTRACT Background The effect of cruciferous vegetables consumption on breast cancer risk is controversial. Cruciferous vegetables are a primary source of glucosinolates that have shown anticarcinogenic effects in etiological studies. Some prior epidemiological and intervention studies suggested the protective effect of crucifers on breast cancer risk but the results were inconsistent. This study evaluated the effect of crucifers on breast cancer risk among women from a familial risk cohort. Methods To address this issue, a hospital-based case-control study was conducted among 200 cases and 200 controls matched on age at baseline and enrollment year, from the same familial risk cohort. A self-developed food frequency questionnaire was applied to assess the consumption of 25 subtypes of crucifers. Adjusted odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated from conditional logistic regression. Cases and controls were stratified by menopausal status and body mass index (BMI, cutoff point 25 kg/m2) and unconditional logistic regression was used in stratified analyses. Results The median consumption of total crucifers was 1 serving/day in cases and less than one serving/day in controls. Total crucifers intake was not associated with breast cancer risk after adjusting for breast cancer risk ii factors. Broccolini showed a protective effect that closed to significance on the development of breast cancer (adjusted OR=0.51, 95% CI = [0.25, 1.01], and P = 0.06). BMI modified the association between total crucifers consumption and breast cancer risk (P = 0.015). Most subtypes non-significantly decreased the odds of developing breast cancer among normal BMI women while non- significantly increased the odds of developing breast cancer among overweight/obese women. Conclusions To the best of our knowledge, this is the first study to examine the impact of cruciferous vegetables on breast cancer risk among women with a familial breast cancer risk and one of the few studies that has collected detailed information on crucifer intake. Total cruciferous vegetables intake was not associated with breast cancer risk among women with a familial risk. Our results suggested that BMI may modify the association between the cruciferous vegetables and breast cancer risk among the high-risk population. iii PREFACE AND ACKNOWLEDGEMENTS In August 2014, I began working toward a Master of Science degree in cancer epidemiology, Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health (JHSPH) in Baltimore, Maryland. To fulfill the requirement of my degree, I worked on my master thesis as a student research in Department of Epidemiology in JHSPH, advised by Dr. Kala Visvanathan. My thesis is focused on examining the association between cruciferous vegetables consumption and breast cancer risk among women with a familial history of breast cancer. Diet is a modifiable risk factor that could therefore be a primary prevention strategy for women with a higher risk due to hereditary factors in addition to other lifestyle factors. A few studies in the general population have shown inverse associations between breast cancer risk and cruciferous vegetables intake. These finding are supported by preclinical studies which suggest that sulforaphane (SFN), a major nutrient of crucifers, has anti-carcinogenic effects. SFN has been shown to inhibit the growth of tumor cells active apoptosis and decrease the expression of key proteins involved in breast cancer proliferation in breast cancer cell lines. There has been no study conducted in women with a familial risk before. To conduct this study, I took advantage of an ongoing cohort study known as the Breast and Ovarian Surveillance (BOSS) Cohort Study which has recruited men and women with a familial risk for breast and/or ovarian cancer from the Johns Hopkins Clinical Cancer Genetics and Prevention Service between 2005 and 2013. I conducted a matched case-control study to explore iv the association between crucifers and breast cancer risk among women with a familial risk. Cases were confirmed by pathology records and medical record. ACKNOWLEDGEMENTS I would first like to thank my thesis advisor, Dr. Kala Visvanathan, for her competent, patient, and kind mentorship during these two years. She helped me in building the idea of my thesis, providing me the dataset for the analyses and providing guidance in the analysis and interpretation of the results with me whenever she thought I needed help. Dr. Visvanathan’s knowledgement and consistently support inspired and encouraged me to overcome many hurdles in my academic career. Acknowledgements are also due to Dr. Avonne Connor, as the reader of my thesis, for her meticulous and valuable comments on my thesis. I would also like to thank the BOSS research team, including Betty May, Brenna Hogan, Alpana Kaushiva, Michelle McCullough, Michele Trieb, Cody Ramin and all the investigators, researchers, and laboratory personnels, for their hardwork and commitment to producing high- quality clean data and generous help for my thesis. Specifically, thanks are due to Alpana Kaushiva for helping me organizing the dataset and discussing the methods and results. Thanks are also due to the patients in BOSS Cohort Study. I thank Aozhou Wu, and all my good friends in JHSPH for their company and support in these two years. Finally, I express my gratitude to my parents for supporting and encouraging me in pursuing the Master of Science degree throughout the two years. The accomplishment would not have been possible without them. Thank you. v TABLE OF CONTENTS ABSTRACT .................................................................................................................. ii PREFACE AND ACKNOWLEDGEMENTS ........................................................... iv LIST OF TABLES ...................................................................................................... vii LIST OF FIGURES..................................................................................................... ix BACKGROUND ........................................................................................................... 1 Summary of Breast Cancer ............................................................................................... 1 Burden of Disease .......................................................................................................... 1 Subtypes of breast cancer ............................................................................................ 2 Established Risk Factors of Breast Cancer .................................................................... 3 Family History of Breast and/or Ovarian Cancer ....................................................... 3 Genetic Risk Factors ...................................................................................................... 4 Environmental Risk Factors .......................................................................................... 5 Reproductive Factors ..................................................................................................... 5 Crucifer Vegetables and its Metabolites .......................................................................... 6 Isothiocyanates ............................................................................................................... 7 Indole-3-carbinol ............................................................................................................. 8 Breast Cancer Risk and Cruciferous Vegetables .......................................................... 8 METHODS.................................................................................................................. 12 Study Design and Population .......................................................................................... 12 Assessment of cruciferous vegetables .......................................................................... 13 Assessment of non-dietary exposures .......................................................................... 14 Statistical Analysis ............................................................................................................ 16 RESULTS ................................................................................................................... 19 Baseline demographics and clinical characteristics .................................................... 19 Cruciferous vegetables consumption and breast cancer risk .................................... 20 Evaluation of the reliability for the FFQ ......................................................................... 23 Change of cruciferous vegetables consumption .......................................................... 24 Sensitivity analysis ............................................................................................................ 24 DISCUSSION and CONCLUSION ......................................................................... 26 Consumption of cruciferous vegetables and breast cancer risk ................................ 26 Consumption of