The Importance of Cancer Prevention Research and its Challenges
, by Barry Kramer, M.D., M.P.H.
The airing this week of Cancer: The Emperor of All Maladies provides a rare opportunity to expand the national conversation around cancer.
A question that inevitably gets raised almost any time cancer is discussed is how we can make greater strides in prevention and early detection. It’s a question much discussed at NCI, and a goal we are pursuing with a diverse and innovative array of approaches.
The target population for cancer prevention and screening interventions is healthy people who have no symptoms. Some of the actions that people can take to lower their risk of getting cancer (do not use tobacco, eat a healthy diet, be physically active, and keep a healthy weight) have wide-ranging health benefits, while other interventions are more specific to cancer and require us to identify who is at risk. Some screening tests are able to find a cancer early enough to intervene and prevent the cancer from becoming life-threatening. We know that the appropriate use of Pap tests, mammograms, and colon cancer screening tests has helped to reduce death rates from cervical, breast, and colon cancers in the United States.
Despite this, we must keep in mind that it is difficult to make healthy people better off than they already are. Preventive interventions must not only work, but also not cause more harm than good. Excessive testing and procedures could inadvertently make people worse off. We must develop strong enough evidence that an intervention provides a net benefit for a healthy person before putting large numbers of people in harm’s way.
Use of increasingly sensitive screening tests can lead to a problem called overdiagnosis. The recently released Annual Report to the Nation on the Status of Cancer includes data on several screen-detected cancers, such as thyroid and melanoma, in which incidence rates are increasing while mortality rates are relatively unchanged, a classic reflection of overdiagnosis. NCI is addressing this issue by supporting studies to identify the cellular and molecular factors that drive progression in screen-detected lesions. This precision medicine approach aims to distinguish cancers that are truly life-threatening and require immediate treatment from those for which treatment is unnecessary.
The NCI supports a broad spectrum of prevention research activities, from generating ideas for scientific study and developing new research methods to the conduct of intervention trials, population studies, and projects to apply positive research results in the real world. The Division of Cancer Prevention is devoted to cancer prevention through support for individual researchers and collaborative research teams and networks. A major program is the NCI Community Oncology Research Program, a national network of investigators, cancer care providers, and academic institutions that brings cancer clinical trials in cancer control, prevention, screening, as well as treatment and cancer care delivery research, to individuals in their own communities.
A growing area of research is focused on cancer immunoprevention, harnessing the body’s ability to heal and protect itself from cancer-causing agents, including infectious causes such as the human papillomavirus. We are also studying interventions that modify the balance of microorganisms in the gut that play a role in energy exchange, inflammation, immunity, and diet. Other new approaches underway include repurposing commonly used drugs such as aspirin to study their effectiveness in cancer prevention. Finally, it is equally important to identify interventions that do not work or are harmful, such as an NCI-supported study that found that Vitamin E increased the risk of prostate cancer.
One of the signature successes of prevention science in the last half century has been the reduction in tobacco use in the United States. The rewards have been a reduction in a large spectrum of cancers and other chronic diseases. But we should not be satisfied. We must continue to support prevention and screening research in a variety of areas that have a positive impact on health care and the potential to reduce cancer incidence and death.
For example, recent NCI-supported research has shown that a low-dose computed tomography (LDCT) screening test can further reduce the risk of dying of lung cancer. Consistent with these study results, Medicare now provides coverage of LDCT lung cancer screening.
Another key element of NCI’s prevention mission is to train the next generation of cancer researchers and to communicate to the public what we have learned through our research programs. Since 1987, the Cancer Prevention Fellowship Program has provided unique opportunities for postdoctoral research training in cancer prevention and control for scientists and clinicians. NCI's free comprehensive cancer database, PDQ® (Physician Data Query), contains peer-reviewed, evidence-based information on a wide range of cancer topics, including screening and prevention summaries that are important sources of information for health professionals, patients, and the public.
Unlike treatment, success in prevention often goes unnoticed by the people who benefit. It is difficult to know when a cancer has been prevented in any given person. Nevertheless, the gratification of scientists working in this field is the recognition that large numbers of people stand to benefit from the evidence and knowledge gained from investments in prevention research.
Barry Kramer, M.D., M.P.H.
Director, NCI Division of Cancer Prevention
This is the second in a series of posts authored by NCI cancer research leaders, inspired by topics covered in the documentary film, Cancer: The Emperor of All Maladies, airing this week on PBS nationwide.
Other Posts in This Series
Looking to the Future of Childhood Cancer Research, by Dr. Malcolm Smith