This was the second annual meeting on prevention held by the American Association for Cancer Research. There were some very exciting press conferences held. Plenary sessions, forums and abstracs offered information about screening, known in these circles as primary prevention, natural products that may be adapted for use in prevention, secondary and tertiary. Chaired by Scott Lippman, Chairman Dept. Of Clinical Cancer Prevention, Professor, Joint Appointment Clinical Cancer Prevention and Thoracic/Head and Neck Medical Oncology, UT M.D. Anderson Cancer Center, Houston, TX, had three presentations. The first was given by James L. Abbruzzese Professor of Medicine and Chair, Gastrointestinal Medical Oncology, UT M.D. Anderson Cancer Ctr. “The Prevention-Therapy Convergence: Phase 1 Drug Development. Dr. Abruzzi told the audience that two important developments suggest that “the early clinical development of anticancer and chemopreventive agents is converging”. He suggested that “...the same biochemical targets that are relevant to patients with advanced cancer are likely to be important during pre-cancer and states of intra epithelial neoplasia.” His innovative suggestion: “...develop strategies where a phase I/II chemoprevention endpoint could be nested or embedded within a phase I or phase II trial of a novel agent in patients with advanced disease.” Ruth B. Etzioni, Member, Fred Hutchinson Cancer Research Ctr., Seattle, WA spoke on “Phases of Biomarker Development”. “Novel molecular technologies are producing a multitude of potentially useful biomarkers. For cancer control researchers, these markers offer promise as screening tests, surrogate endpoints, and tools for early diagnosis of treatment failure or disease recurrence. Different types of studies are required for discovery, development and evaluation of new biomarkers.” She suggested identifying promising markers, developing tests for practice, validation (evaluate on stored tissue removed before cancer diagnosis), then evaluate in humans to eliminate false negatives. Systems include cDNA micro arrays, BAC arrays, proteomics, tissue micro arrays or comparison of blood samples of those with and without cancer. Many of these are currently in phase I studies. The final talk of this session was given by Ernest T. Hawk, Chief, Gastrointestinal and Other Cancers Research Group, National Cancer Institute/Division of Cancer Prevention, Bethesda, MD on “Defining Primary, Secondary and Tertiary Prevention”. Dr. Hawk told the audience that after reviewing eight major publications in epidemiology, he and his team found inconsistent use of the three terms (above). He further stated that many of the commonly used terms are not well defined. Examples included validation - what is implied? To what extent? And how? (He suggested that IEN lesions [Intra epithelial Neoplasia] could serve as a meaningful endpoint. Prevention, whether in absolute or relative risk terms (he stated that prevention and risk reduction were the same to him). Biomarker - Of what? For what? And if validated, how? Cohort, asymptomatic, average risk, disease-free, healthy. He defined Primary prevention as preventing incidence in healthy people. Secondary -screen to identify those with subclinical disease and intervene early to modify the course of progression. Tertiary - promote adaptation in patients with the disease (similar to therapeutics). Other morning Educational sessions included: Methodological Challenges in Population Studies, and Molecular Technologies as Applied to Prevention Studies. During Forum #4 “Chemoprevention of Breast Cancer”, Steven H. Safe, Dir., Ctr for Env and Genetic Medicine, Institute of Biosciences and Technology, Texas A& M University System Health Science Center, discussed their diim product (their version of an Indole-3-carbinole) which is non-toxic. He said that this product completely inhibited MCF-7 cell growth. Other Forums on Monday, October 27 included: Chemoprevention of Gastrointestinal Cancer, Chemoprevention of Melanoma, Chemoprevention of Lung, Head and Neck Cancers. Presidential Symposium “Global Perspectives in Cancer Prevention Research”, by Paul Kleihues, International Agency for Research on Cancer, Lyon, France. From the abstract: “The main reasons for the greater cancer burden in affluent societies are the earlier onset of the tobacco epidemic, the earlier exposure to occupations carcinogens, and the Western nutrition and lifestyle.” “In industrialized countries, approximately 30% of malignant tumors are due to the Western nutrition and lifestyle, characterized by a high caloric diet, rich in animal fat combined with low physical activity. Tumors associated with the Western lifestyle include cancer of the breast, prostate, colon, rectum and endometrium.” Harald zur Hausen,Scientific Dir., German Cancer Research Ctr, Heidelberg, Germany, spoke on “Infection and Cancer Prevention” pointing out that...”approximately 20% of the global cancer incidence appears to be caused by infections.” (HPV for cervical cancer, anogenital cancers and 25% of oral cancers, HHV-8 in Lymphatic, nasophyrangeal, Kaposi sarcomas, and some gastric cancer, Hepatitis B/C linked to hepatocellular cancer.HTLV-1 is linked to adult T-cell leukemia. Bacteria such as Helicobacter pylori is linked to gastric cancer, and parasites have been linked to bladder, anorectal and bile duct cancers. Vaccines such as Hep B and human papillomaviruses were mentioned. John Potter Sr. Vice President, Dir. Div of Public Health Sciences, Fred Hutchinson Cancer Research Center, Prof of Epidemiology, U of Washington, Seattle, WA, made a presentation on “Nutrition and Cancer” Symposiums followed: “Prevention in Cancers of Increasing Concern: Premise, Progress and Prospects” which featured discussions on Barrett’s Esophagus, Melanoma and Liver Cancers. “Understanding Tobacco and Cancer Through Transdisciplinary Science” “Molecular Imaging in Small Animal Models of Cancer” “Cancer Prevention for Aging Populations” Judith Campisi, Senior Scientist, Lawrence Berkeley National Laboratory, Berkeley, CA and Prof, Buck Institute for Aging Research, Novato, CA, spoke on “Cancer and Aging: Basic Biologic Relationships”. She said that tumor suppressors were valuable when an organism was young but no longer good or useful as it aged. She asked whether tumor suppressors and aging could be uncoupled? Blood vessels do not develop as easily in an aged organism, so vascularization of a tumor was reduced. Wendy Demark-Wahnefried spoke on “Lifestyle Changes for Cancer Prevention in Older Adults”. 61% of cancer cases are diagnosed at age 65 or older. She pointed out that elders are also at increased risk for developing ‘side’ effects (call them unwanted), from “chemotherapeutic approaches, thereby reducing the benefit to risk ratios of current pharmacologic interventions (example: increased risk of deep vein thrombosis and endometrial cancer among elderly tamoxifen users).” She suggested that lifestyle interventions, such as smoking cessation, increased physical activity, decreased energy intake and improved diet quality “may offer more promise in this high risk population”. She also reminded the audience that the elderly are most often underrepresented in behavior intervention trials (most other types of trials as well). Dr.D- W made the point that multiple-risk factor interventions has already been studied (Berrigan et al Prev Med 36:615,2003). Monday evening featured Poster sessions (see below for some of them). |
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