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Breast Cancer Prevention Art or Science? Kristi McIntyre M.D. Texas Oncology 2005
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Patient 59 year old healthy Caucasian postmenopausal female with recent abnormal screening mammogram. She is asymptomatic. No family history of breast cancer Uses deodorant No significant health issues ; normal bone density Has chronic sinusitis and takes antimicrobials frequently Biopsy of breast shows atypical ductal hyperplasia Gail risk 3.5.%
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You Choose: Start Raloxifene Start Tamoxifen Wait several months and reassess Clinical trial No therapy but observation and surveillance
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Breast Cancer Risk Factors
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Breast Cancer Incidence
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How much of Breast cancer is Hereditary? Hereditary Sporadic 5-7% 15-20% Familial clusters
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Family history and breast cancer risk Most hereditary breast cancers arise from mutations in BRCA1 and BRCA2 Autosomal dominant, tumor suppressor gene Age breast cancer <50 Bilaterality Male breast cancer ovarian cancer Multiple other cancers Ashkenazi Jews
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Reproductive Factors and Breast Cancer Menarche Menopause Menarche <15 OR 1.2 Menopause >50 OR 1.5 Null parity OR 2.0 Breastfeeding 4.3% decrease risk/yr First live birth<20 OR 0.5 First live birth >30 OR 1.5 Postmenopausal Estradiol levels
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WHI Trial of Estrogen plus Progestin E+P placebo p-value Invasive Breast cancers 199 150 0.003 Abnormal Mammograms 716 395 0.0001 SEER high stage 25% 16% 0.041 More breast cancers diagnosed at more advanced stage and increased abnormal mammograms Chlebowski JAMA 2003;289. 3243
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Benign Breast Disease Nonproliferative 1 Proliferative,no atypia 2X Atypical Hyperplasia 4X In Situ 10-20X Histology RR
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ASCO 2005 Cuzick L
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Lifestyle factors and breast cancer risk Body mass index: postmenopausal women >30% excess BMI increased risk Dietary fat intake: increased risk NSAID use: decreases risk Physical activity: 1.25 to 2.5/hrs week brisk walking had 18 % decrease risk Alcohol use: increased (dose dependent)
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Chemoprevention of breast cancer Can we find an ideal agent? Who should take it?
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Mechanism of Disease: Estrogen Carcinogenesis; Yager et al NEJM Jan 2006
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Smith, I. E. et al. N Engl J Med 2003;348:2431-2442 Mechanism of action of Tamoxifen
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NSABP B-24 TRIAL
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NSABP P-1
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*50% reduction
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BCPT results: bone and endometrial cancer events Bone fractures Endometrial cancers 5.4 13 111 137 placebo Tamoxifen
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Multiple Outcomes Raloxifene Evaluations Study
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Multiple Outcomes Raloxifene Evaluation TRIAL Breast cancer risk reduction :76% Raloxifene Placebo
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STAR trial objectives Evaluate the effect of Tamoxifen vs. Raloxifene in reducing the incidence of: Invasive breast cancer Noninvasive breast cancer Endometrial cancer Vascular events Bone fractures
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Smith, I. E. et al. N Engl J Med 2003;348:2431-2442 Aromatase Inhibitors
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Smith, I. E. et al. N Engl J Med 2003;348:2431-2442 Classification of Aromatase Inhibitors
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Aromatase Inhibitor adjuvant trials and contralateral breast cancer incidence
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Aromatase Inhibitors : Adverse effects compared to Tamoxifen
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Aromatase Inhibitor Prevention Trials IBIS -II MAP - 3 Arimidex Placebo Exemestane placebo 6,000 postmenopausal women 5000 postmenopausal women
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2 Tamoxifen Raloxifene ? Aromatase Inhibitor NSABP P-4 Future Breast cancer Prevention trial Spring 06
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Conclusions Chemoprevention will have a tremendous impact on breast cancer incidence Refining criteria of “high risk patient” and measurable surrogate markers LOOK FOR RESULTS STAR trial Encourage clinical trial participation P-4
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