Screening is typically considered to be a worthy effort for diseases that are both true killers and commonly remain asymptomatic until they have advanced to stage 3 or 4. This has proven to be the case for colorectal cancer screening, which has been found to be associated with reductions in mortality. Lung cancer screening, which is associated with a 16% relative reduction in lung cancer-specific mortality, would seem to also fit the bill. Yet it remains controversial.
Why is that? For one, lung cancer screening is based on a more difficult set of screening criteria to operationalize in practice. Two, lung cancer suffers from the ignominy of being a "sin" cancer, one that largely depends on exposure to tobacco smoking. That these cases are most densely reported in Appalachia, along the Mississippi river, and in Arkansas may also skew the statistical perspective and professional experience of some policy-makers and researchers, who often lack familiarity with these regions. Some experts have begun a clamor to eliminate coverage for lung cancer screening.[2,3]
Although all these factors certainly affect screening rates, lung cancer screening efforts are principally hindered by the reality that many primary care providers do not understand the screening guidelines.
Unlike some other cancer screening guidelines, the criteria for lung cancer screening do not depend on age alone as an eligibility determinant. In fact, lung cancer screening is a complicated undertaking requiring a complicated set of steps, as the 10-pillar lung cancer screening model developed at Massachusetts General Hospital clearly illustrates (Figure 1).
For lung cancer screening to be an effective and sustained offering, both clinicians and the healthcare system will need to improve. An older study of primary care physicians found that almost one half ordered chest radiography as a screening tool, despite the lack of evidence demonstrating efficacy of radiography as a screening test for lung cancer. And a recent presentation at the American Society of Clinical Oncology conference noted that only 2% of high-risk patients are currently being referred for low-dose CT screening.
One Size Does Not Fit All
Although smoking rates have been declining for several years, there are wide variances across the country. The incidence of smoking, smoking patterns, and cessation ratios differ between genders and regions.
Not surprisingly, that means lung cancer rates also vary.
The American Cancer Society estimates that 14% of all new cancers will be lung cancers this year alone, an estimated 154,050 people will die of lung cancer. Although overall 5-year survival is only 18.6%, that improves to 55% for cases diagnosed at an early, local stage.
The National Lung Screening Trial enrolled over 50,000 current or former heavy smokers (30 pack-years or more) who were randomly assigned to be annually screened with either low-dose CT or posteroanterior chest radiography for 3 years. Patients screened with low-dose CT had a relative reduction in mortality from lung cancer of 20%.
One would expect that the emergence of a successful method of screening would be embraced. Indeed, the US Preventive Services Task Force, the American Association for Thoracic Surgery, the American College of Chest Physicians, the National Comprehensive Cancer Network, the Medicare Evidence Development and Coverage Advisory Committee, and the American Cancer Society have all recommended low-dose CT under very specific circumstances, though the eligibility criteria cited in each vary a bit in the details.
And therein lies the rub: the details. The need for screening is less obvious in some areas of the country. The view in San Diego County, an area with fewer smokers, little exposure to radon, and other factors that support good health, is quite different from what is seen in the "black" risk states of Kentucky and West Virginia. Yet, no guidelines take into account these regional variances in risk. The highest-risk regions face additional barriers in accessing screening and coordinating care and appropriate follow-up.
When screening is conducted improperly, there is an inherent risk for harm. This includes radiation exposure, false-positives, and dangers inherent in the evaluation of positive findings, a risk that is compounded by substantial population variances.
The risks associated with screening also include emotional costs. However, it is germane that the risks of lung cancer and other maladies are no secret to smokers. In regions with high levels of smoking and lung cancer, individuals are painfully aware of, and almost fatalistic about, the toll of smoking and lung cancer. The greater challenge is inspiring hope and breaking down access barriers common to poor and rural populations.
Screening can be a relief to patients; however, the need for annual follow-up must be emphasized. It is essential that the screening efforts be paired with appropriate psychological support and smoking cessation efforts. Such efforts do incur cost, but the return on that investment may include reductions in smoking as well as the incidence and prevalence of other tobacco-related afflictions.
Medscape Family Medicine © 2019 WebMD, LLC
Any views expressed above are the author's own and do not necessarily reflect the views of WebMD or Medscape.
Cite this: Lung Cancer Screening: One Size Does Not Fit All - Medscape - Jan 17, 2019.