Diet, Lifestyle and Breast Cancer Risk Barbour S Warren, PhD Program on Breast Cancer & Environmental Risk Factors Sprecher Institute for Comparative Cancer Research

1) Biology of the development of breast cancer 2) Risk factors for breast cancer (in light of the biology) 3) Potential for modification of breast cancer risk Overview

Initiation PromotionProgression Mutation Cancer Gene Proliferation Independence Mutation Invade & Spread Stages of Cancer Formation Unspecialized Cell Initiated Cell Benign Tumor Malignant Tumor Latency Period, 20 years or more

Development of the Breast Ductal Tree Differentiation Occurs With Pregnancy 2 years After Puberty After Pregnancy Proliferation Differentiation Proliferation Birth

Proliferation Differentiation Proliferation and Differentiation A Ying-Yang Relationship in Breast Cancer Formation

Proliferation – Cell Multiplication Essential for normal growth & development of the breast Important factor in breast cancer Allows less time for mutation repair The key event during tumor promotion

Proliferation Decreases Mutation Repair Time For Repair Before DNA Duplication Little Time For Repair Before DNA Duplication Within a Cell In Each Daughter Cell

Proliferation – Cell Multiplication Essential for normal growth & development of the breast Important factor in breast cancer Decreases time for mutation repair Estrogen and other reproductive hormones cause proliferation of breast cells Key event during the tumor promotion Proliferating cells at risk to undergo initiation, promotion and progression stages of cancer formation

Proliferation Differentiation Proliferation and Differentiation A Ying-Yang Relationship in Breast Cancer Formation

Development of the Breast Ductal Tree Differentiation Occurs With Pregnancy 2 years After Puberty After Pregnancy Birth Lobules

Puberty Sexual Maturity PregnancyLactation Terminal End Bud Lobule Type 1 Lobule Type 2 Lobule Type 3 Lobule Type Level of Proliferation Differentiation of A Breast Lobule Growth to a Functioning Entity

Cells at Risk Are Analogous to a Target’s Bull’s-eye Carcinogens A larger number of cells at risk produces a larger (and easier to hit) bull’s-eye.

Interaction of a Cell at Risk with a Carcinogen Can Produce an Initiated Cell An initiated cell is the first step in formation of a tumor For an initiated cell to become a tumor both the Promotion and Progression stages have to occur The larger the number of initiated cells the higher the breast cancer risk

Estrogen Estrogen acts with other reproductive to increase proliferation in the breast Proliferation is linked to: Tumor promotion Decreased mutation repair Increases in the number of ‘cells at risk’ Estrogen may be metabolized to form a carcinogen which could cause mutations and form initiated cells Relation to Breast Cancer Risk

How Is The Risk Of Breast Cancer Increased? 1)Larger number of mutations Increased initiation & progression 2) Greater level of proliferation Increased promotion & progression 3) Increase number of cells at risk to become breast cancer 4) Increase the time of high risk for tumor initiation

Vegetables and Fruits Eating large amounts of vegetables, in general, may be linked to a small decrease in breast cancer risk Supplements do not appear to offer the same protection as food Evidence is stronger for a decrease in risk with dark green and yellow vegetables Eating fruit, in general, is unrelated to breast cancer risk Vegetables may have a greater effect for women with a family history of breast cancer

Anti-cancer Agents in Vegetables & Fruits Inhibition of Initiation Stage of Cancer Formation

Initiation PromotionProgression Mutation Cancer Gene Proliferation Independence Mutation Invade & Spread Stages of Cancer Formation Unspecialized Cell Initiated Cell Benign Tumor Malignant Tumor Latency Period, 20 years or more

Anti-cancer Agents in Vegetables & Fruits Inhibition of Initiation Stage of Cancer Formation A) Block carcinogen activation Flavonoids and isoflavonoids Coumarins Isothiocyanates in cruciferous vegetables Organosulfur compounds in garlic & onions B) Enhance carcinogen detoxification Antioxidants in plants Isothiocyanates in cruciferous vegetables Organosulfur compounds in garlic & onions C) Increase DNA repair Polyphenols in green tea Selenium

Initiation PromotionProgression Mutation Cancer Gene Proliferation Independence Mutation Invade & Spread Stages of Cancer Formation Unspecialized Cell Initiated Cell Benign Tumor Malignant Tumor Latency Period, 20 years or more

Anti-cancer Agents in Fruits & Vegetables Inhibition of Promotion Stage of Cancer Formation A) Scavenge reactive oxygen species Antioxidants in plants B) Alter proliferation & differentiation Phytoestrogens (+/-) Retinoids

Physical Activity May be associated with decreased breast cancer risk for women of all ages Thought to possibly act by changing: 1)Menstrual activity Exercise may increase age at menarche 2) Body characteristics Exercise can decrease body fat 3) Hormone levels Exercise may decrease estrogen levels

Smoking Tobacco Effect of adult smoking (active & passive) is unclear Age beginning smoking may be important Heavy smokers below age 20 have a 30% to 80% increase in breast cancer risk Cigarette smoke contains numerous chemical which can initiate and promote cancer Breast fluids of smokers contain chemicals from cigarette smoke

Alcohol Use Adult use associated with risk (about 10% increase for each drink per day) All studies have reported impact of early age alcohol use on breast cancer risk About twice the risk of breast cancer for women below 35 years Alcohol use increases estrogen levels Adequate folic acid (B vitamin) may decrease risk in women who have more than 1 drink per day

Obesity –Associated with decreased premenopausal breast cancer risk (25% decrease) Interferes with regular menstrual cycling Less proliferation in breast –Associated with increased postmenopausal breast cancer risk (about 200% increase) Increases estrogen exposure Fat cells form estrogen from other hormones

InitiationPromotion Mutation Cancer Gene Proliferation Independence Modifying the Stages of Cancer Formation Unspecialized Cell Initiated Cell Benign Tumor Decrease Initiation Process 1) Minimize Exposures 2) Childbirth 3) Diet 4) Avoid radiation exposure Decrease cells at risk 1)Childbirth 2)Diet? Eliminate Initiated Cells 1)Childbirth? 2)Diet? Decrease Promotion Process 1)Decrease estrogenic exposures 2)Childbirth 3)Diet 4)Physical Activity