Colonoscopies screen for colorectal cancer by detecting early, curable cancers. Precancerous adenomas -- a type of colon polyp -- can also be detected and removed, thereby preventing cancers from developing.
"We found that higher levels of detection were associated with a decreased subsequent risk of cancer," said Douglas A. Corley, MD, PhD, a gastroenterologist and research scientist with the Kaiser Permanente Division of Research. "Taking out adenomas prevents cancers, and early detection likely prevents many cancers."
The study is the largest ever conducted and the first in the United States to examine the relationship between detecting adenomas and the future risk of colorectal cancers.
Colorectal cancer is the second-leading cause of cancer death in the United States. According to the American Cancer Society, about 137,000 new cases are diagnosed each year in the United States with 50,000 deaths. Colonoscopy every 10 years is one of three screening methods recommended by the U.S. Preventive Services Task Force; the others are sigmoidoscopy every five years or annual fecal testing.
The colonoscopies studied were performed on Kaiser Permanente patients between Jan. 1, 1998 and Dec. 31, 2010, in Northern California. All patients were age 50 or older and had at least six months of follow-up after their colonoscopy. The gastroenterologists were experienced: All had completed at least 300 colonoscopies, and each performed an average of 2,150 colonoscopies per year.
Among the nearly 264,972 colonoscopies studied, 712 patients were subsequently diagnosed with a colorectal cancer after being followed for up to 10 years after their exam; these included 255 advanced-stage cancers and 147 deaths.
Researchers found that for each 1 percent increase in adenoma detection rate, there was a 3 percent decrease in colorectal cancer risk.
Dr. Corley said the study confirms that adenoma detection rates are an accurate quality metric for clinicians performing colonoscopies: "Given these results, to maximize the effectiveness of our screening programs, we have been providing feedback to physicians for three years as well as developing new methods to maximize detection rates."
Kaiser Permanente can conduct transformational health research such as this study in part because it has the largest private patient-centered electronic health system in the world. The organization's electronic health record system, Kaiser Permanente HealthConnect®, securely connects 9.1 million patients to 16,000 physicians in almost 600 medical offices and 38 hospitals. It also connects Kaiser Permanente's research scientists to one of the most extensive collections of longitudinal medical data available, facilitating studies and important medical discoveries that shape the future of health and care delivery for patients and the medical community.
The study was undertaken within the National Cancer Institute's Population-based Research Optimizing Screening Through Personalized Regimens consortium, a multisite effort to evaluate and improve cancer-screening processes; Kaiser Permanente Northern California is a lead site for this study.
This research was supported in part by a grant from the National Cancer Institute.
In addition to Dr. Corley, co-authors of the study were Christopher D. Jensen, PhD, Amy R. Marks, MPH, Wei K. Zhao, MPH, Jeffrey K. Lee, MD, Jolanda de Boer, MB, Bruce H. Fireman, PhD, Theodore R. Levin, MD, and Charles P. Quesenberry, PhD, all of the Kaiser Permanente Division of Research; Joanne E. Schottinger, MD, Virginia P. Quinn, PhD, and Nirupa R. Ghai, PhD, all of Kaiser Permanente Southern California Research & Evaluation; Chyke A. Doubeni, MD, MPH, University of Pennsylvania Perelman School of Medicine; and Ann G. Zauber, Memorial Sloan-Kettering Cancer Center.
About the Kaiser Permanente Division of Research
The Kaiser Permanente Division of Research conducts, publishes and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and society at large. It seeks to understand the determinants of illness and well-being, and to improve the quality and cost-effectiveness of health care. Currently, DOR's 550-plus staff is working on more than 250 epidemiological and health services research projects. For more information, visit www.dor.kaiser.org and follow us @KPDOR.
About Kaiser Permanente
Kaiser Permanente is committed to helping shape the future of health care. We are recognized as one of America's leading health care providers and not-for-profit health plans. Founded in 1945, our mission is to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We currently serve approximately 9.1 million members in eight states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal physicians, specialists and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the-art care delivery and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education and the support of community health. For more information, go to kp.org/share.
Web Site: http://www.dor.kaiser.org
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