Cancer screening has saved many lives, but there are challenges in developing and implementing high-quality screening programs for the general population. The National Cancer Policy Forum (NCPF) of the National Academies of Sciences, Engineering and Medicine explored those challenges at a workshop in Washington, D.C.
Workshop speakers stressed that the evidence bar has to be set very high for asymptomatic people, and they highlighted opportunities to improve the evidence base for cancer screening. Speakers also discussed complexities in developing new screening tests, the importance of shared decision-making in screening decisions, and strategies to improve access to high-quality screening for vulnerable and underserved populations. A written summary from the workshop will be forthcoming.
Asked to describe his goal for the meeting, workshop Co-Chair and NCPF member Stanton L. Gerson, MD, told Oncology Times, "We wanted to air the complexity and dynamics of cancer screening, given that it is the most common test most people get." Gerson, Director of the Case Comprehensive Cancer Center and Tripp Professor of Hematological Oncology at Case Western Reserve University, added that, in general, cancer screening is "very understudied."
Evidence of a reduction in mortality from a randomized controlled clinical trial is the only true way to assess the benefit of a cancer screening procedure, stressed NCPF member Otis W. Brawley, MD, MACP, FASCO, FACE, the Bloomberg Distinguished Professor of Oncology and Epidemiology at Johns Hopkins University and former Chief Medical and Scientific Officer at the American Cancer Society (ACS).
Brawley, a member of the workshop planning committee, noted that many people who undergo cancer screening do not understand its potential risks. These include false-positive results leading to a workup with its attendant morbidity and adverse side effects; and detection of small lesions that do not pose a threat to the patient but can lead to overdiagnosis and unnecessary medical treatment such as biopsies. "There's some really harsh history out there," noted Brawley, author of the book How We Do Harm.
"We have to follow the science," said Brawley, urging caution in introducing any new cancer screening technologies into the general population. Agreeing was Barnett Kramer, MD, MPH, former Director of the Division of Cancer Prevention at the National Cancer Institute (NCI). When the incidence of a cancer goes up, that could actually be due to overdiagnosis, noted Kramer, who served on the steering committee for two large NCI-sponsored cancer screening trials, the Prostate, Lung, Colorectal, Ovarian Cancer Screening Trial and the National Lung Screening Trial (NLST).
The problem of overdiagnosis due to cancer screening is not insignificant and constitutes a public health problem. According to data from NCI's Early Detection Research Network, which conducts research on cancer biomarkers, about 25 percent of breast cancers detected on mammograms and about 60 percent of prostate cancer detected with prostate-specific antigen tests could represent overdiagnosis.
Kramer said much more education is needed about the problem of overdiagnosis due to cancer screening, and he recommended that in some cases terminology should be changed for a lesion found on screening and likely to pose no threat-such as "indolent lesion of epithelial origin." Strategies such as active surveillance for prostate cancer can be used when appropriate to avoid overdiagnosis, he added. Kramer emphasized that more research is needed to learn more about the biology of tumors in order to distinguish which are likely to become life-threatening and which are not.
"Evidence for screening has to be very high," stressed Alex Krist, MD, MPH, Professor of Family Medicine & Population Health at Virginia Commonwealth University, Chair of the U.S. Preventive Services Task Force (USPSTF), and a member of the workshop planning committee. Krist noted that most people won't get the cancer they are being screened for, but they are subject to the test's potential harms. He noted that all of the USPSTF screening recommendations rely heavily on evidence from randomized controlled trials showing the certainty of a net benefit and the magnitude of a net benefit.
In an era of promising cancer biomarker discovery, it could be tempting to want to adopt new cancer screening tests prematurely. But claims about new screening tests often fail, cautioned David D. Ransohoff, MD, Clinical Professor of Epidemiology at the Lineberger Comprehensive Cancer Center and Professor of Medicine in the Division of Gastroenterology and Hepatology at the University of North Carolina, Chapel Hill. He cited failed proteomics blood tests for ovarian cancer and prostate cancer, as examples, and stressed the need for scrupulous evaluation and validation of biomarkers for early cancer detection before they could be considered for a screening test for the general population.
Speakers emphasized that individual patient characteristics, values, and preferences should be taken into consideration in cancer screening. "No single perspective represents the interests of all participants in value-based decisions about screening," said Jeanne Mandelblatt, MD, PhD, Professor of Medicine and Oncology at Georgetown University. She noted that advanced age and the presence of co-morbidities affect cancer screening decisions, such that older people with a number of medical conditions should consider stopping screening earlier.
Today, cancer screenings can take place at public venues such as health fairs, which reach a wide audience. But, "I do believe screening belongs within a clinician/patient relationship," said J. Leonard Lichtenfeld, MD, MACP, Deputy Chief Medical Officer for the ACS at the society's global headquarters in Atlanta. "I think we need to look at this a lot more holistically as part of a system," he told Oncology Times.
Lichtenfeld noted that to develop a screening program for a patient requires effort on the clinician's part and depends on awareness and specific knowledge about that patient. He said a cancer screening recommendation should be given by a trusted health professional in the context of the patient/clinician relationship. Lichtenfeld emphasized the importance of high-quality, timely follow-up in an efficient health system if the patient receives an abnormal result from a cancer screening.
Agreeing on the need for high-quality, timely follow-up if cancer screening shows an abnormality was Ann M. Geiger, MPH, PhD, Scientific Director of Cancer Care Delivery Research in NCI's Community Oncology Research Program. "If you don't have something happen, then it's pretty pointless to get the test in the first place," she said.
Geiger noted that, unfortunately, there is a substantial group of patients who do not follow up after receiving a report of an abnormal finding on a cancer screening test.
"It's about health systems, not just screening," she said, agreeing with Lichtenfeld. Geiger said that insurance coverage is a real issue in terms of follow-up, especially for the uninsured and underinsured. She also noted that organizational, communication, and clinical workflow factors could play a role in the lack of timely follow-up, especially if a clinician does not receive the patient's abnormal screening result.
Several speakers addressed the challenges and complexities of bringing cancer screening to vulnerable and underserved populations. Issues such as lack of access to services in their community, lack of transportation, lack of child care, lack of insurance, low income, and fear and mistrust of the health system can all play a role in whether underserved people are screened for cancer, said Capt. Jacqueline Miller, MD, FACS, Medical Director of the National Breast and Cervical Cancer Early Detection Program in the Division of Cancer Prevention and Control of the CDC.
Miller said that, for underserved populations, interventions such as after-hours clinics, reminder systems, and community health workers may be necessary and may improve cancer screening rates. She also emphasized that health care workers need to show that they accept and respect the identity of the people they are screening.
"No woman should die of cervical cancer," emphasized Kathleen Schmeler, MD, Professor in Gynecologic Oncology and Reproductive Medicine at the University of Texas MD Anderson Cancer Center.
She described a collaborative initiative begun in 2015 to increase cervical cancer screening and treatment in the Rio Grande Valley of Texas along the Texas/Mexico border, which has a high Hispanic population and a high proportion of residents living below the poverty line. Cervical cancer rates of women in this area are about 30 percent higher than they are in the rest of Texas. The initiative also includes school-based HPV vaccination.
"We do a lot of hands-on training," said Schmeler, who is co-leader of Project ECHO (Extension for Community Healthcare Outcomes), which uses video conferencing to link MD Anderson faculty in Houston with Rio Grande Valley clinicians to discuss patient cases and teach medical techniques.
In 2017, the NCPF published a report from its 2016 workshop on implementation of lung cancer screening. That 2016 workshop followed the 2011 release of results from the NCI trial NLST showing a 20 percent reduction in mortality from lung cancer for patients screened with low-dose computed tomography (LDCT).
Based on these results, in 2013, the USPSTF recommended annual lung cancer screening with LDCT for asymptomatic people at high-risk of developing lung cancer, such as heavy smokers. That NCPF report concluded that lung cancer screening is "not a single test, but a complex process dependent on multiple steps," including shared decision-making, interpreting results, providing diagnostic follow-up tests when needed, and treating patients diagnosed with cancer. The NCPF report on lung cancer screening states, "Successful completion of each one of these steps is necessary for the maximal screening benefit to be realized."
Based on the discussion at the recent NCPF meeting on cancer screening, that 2017 conclusion is applicable today and can be applied to implementation of any current or new cancer screening test designed for use in the general population.
Peggy Eastman is a contributing writer.