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Cancer Prevention: Clinical Trials. Christina Laukaitis, MD, PhD, FACP 22 June 2012.
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Cancer Prevention: Clinical Trials Christina Laukaitis, MD, PhD, FACP 22 June 2012
To continue to increase the competitive stance of cancer research and training at Northern Arizona University by adding new cancer researchers and by continuing strong faculty development programs for all junior faculty. • To develop programs that facilitate the successful transition of Native American students into the universities and that enhance the retention and graduation of Native Americans undergraduates in biomedical sciences. • To develop sustainable community education programs and research for cancer prevention that meet the unique needs of the Hopi Tribe and the Navajo and Tohono O’odham Nations. NACP Specific Aims
Analysis of the roles of genes and chromosome rearrangements in genomic instability • Uranium as environmental risk factor for cancer among the Navajo • Allostery, protein complexes and cellular distribution for the Nitric Oxide Receptor & soluble GuanylylCyclase Research program
Focused on transitioning Native American students into undergraduate work at Partnership institutions and preparing them to enter graduate programs in biomedical sciences through a research-based training program • Summer research program • NAU or UA • Stipend & mentoring provided Training program
Developing a continuing education curriculum for community healthcare workers • Identifying resource and educational needs of healthcare providers, and partnering to fill those needs • In collaboration with IHS, a ‘virtual’ colon cancer screening program has been created in remote areas of the Navajo Nation Community outreach program
Family history/genetics Behaviors (e.g. smoking) Exposures (e.g. uranium, HPV) Medical issues (e.g. diabetes, obesity, previous cancer) At-risk person Person with cancer Intervention
Choose an appropriate group to study • Elevated baseline risk • Develop an appropriate intervention • Likely to change physiology of disease • Side effect minimal/tolerable • Intervene at the right time • Before pre-cancerous changes are irreversible • Follow up for an appropriate time-period Keys to a successful prevention trial
Breast cancer prevention • 16,000 women at high-risk of breast cancer • ½ treated with placebo, ½ with tamoxifen • After 5 years, breast cancer rates were ½ for those treated with tamoxifen versus placebo Invasive breast cancer rates in women at high risk 40 30 20 10 0 Placebo Cumulative number of cases (per 1000 women) Tamoxifen 0 1 2 3 4 5 6 Years
Raloxifene has similar benefits to tamoxifen Fisher et al., JNCI 2005 Vogel et al., JAMA 2006
Tamoxifen Good effects • Reduces breast cancer risk • Lowers LDL cholesterol • Strengthens bones Bad effects • Increases uterine cancer risk • Increases blood clot risk Benefits and risks of tamoxifen Kleinsmith et al. NCI 2002
Raloxifene • Good effects • Lowers LDL cholesterol • Reduces risk for invasive breast cancer • Strengthens bones • Fewer uterine cancers than tamoxifen • Fewer blood clots than tamoxifen • Bad effects • No relief for hot flashes • No reduction of LCIS • No reduction of DCIS Raloxifene has different risks Kleinsmith et al. NCI 2002
Behavioral interventions for risk factors • Nutritional supplements • Vaccinations against infectious cancer causes • Medications for people at high-risk • Eliminating pre-cancerous cells • Intensive screening to identify cancer early Interventions
Test whether intervention reduces cancer rates • Inherently difficult • Measuring something that DOESN’T happen • May be many years before see effects • Difficult to determine cause v. chance Prevention Trials
I didn’t have an accident today ;) • June in Tucson v. January in Flagstaff Choose appropriate subjects
Gail Model Gail et al., JNCI 1989
Average risk • ~12% lifetime risk • 1/8 women will develop breast cancer in her life • Moderate risk • <5x average risk • 15-25% lifetime • 1 first-degree relative >60, obese, alcohol use, etc. • High risk • 5-10x average risk • Lifetime risk >25% by Claus & >50% by Gail models • LCIS, ADH, ALH; 2 first-degree relatives, or 1 <60 • Very high risk • >10x average risk • >50% lifetime risk • BRCA1 or BRCA2 mutation or other syndrome Risk categories Schwartz et al., The Breast J 2007 Schwartz et al., Cancer 2007 Zakhireh et al., Eur J Cancer 2008
Breast cancer prevention • Vitamin D • Deficient pre-menopausal women with elevated baseline risk • Outcome: breast density • Broccoli extract • Post-menopausal women with elevated risk on tamoxifen • Outcomes: breast density & tamoxifen tolerability • Letrozole (dose-finding Phase I trial) • Post-menopausal women with elevated breast cancer risk • Outcomes: side effects & pathology on random fine needle aspirate Ongoing trials at UACC
Lifestyle modification • Intensive screening • Chemoprevention • Prophylactic surgery Potential Risk Potential Benefit Risk Benefit Risk reduction strategies