What Is the Best Approach to Lung Cancer Screening of High-Risk Smokers?
Ronald Rubin, MD—Series Editor, and Trent Wang, DO
Rubin R, Wang T. What is the best approach to lung cancer screening of high-risk smokers? Consultant. 2016;56(9):815-816.
A young woman accompanies her 60-year-old father during his visit for a routine checkup. She mentions that the recent death of a family friend from lung cancer has her concerned about her father’s health, given that he is a lifelong active smoker. The patient’s daughter begins inquiring about the potential role of lung cancer screening for her father, since she says she has heard a lot of news reports on television about this topic.
Answer: C. Lung cancer screening with low-dose helical CT scanning should be conducted in high-risk individuals after an informed discussion of benefits and risks.
Lung cancer remains the No. 1 cause of cancer mortality in the United States, with some stunning statistics even now that public health and financial initiatives to lessen cigarette smoking have finally begun to take hold. Recent reviews report that lung cancer accounts for 27% of cancer mortality in the United States, that up to one-third of heavy smokers will die from lung cancer, and that 85% of lung cancer cases are a result of smoking.1 These morbidity and mortality data make lung cancer a prime candidate for screening if an efficacious method for doing so can be found.
In order for any screening scheme to be truly worthwhile, it must be able to detect asymptomatic disease, when the disease is more amenable to effective therapy. The screening scheme must carry a minimum of harm, such as excessive false-positive results and overdiagnosis (which is quite important in lung cancer, where therapy can be quite difficult and morbid for the patient). And finally, any effective screening scheme must ultimately translate into actual decreased morbidity and mortality, rather than merely the early detection of more cancers without such a benefit.
Over the years, a variety of attempts to effectively screen for lung cancer have been evaluated. The initial screening method centered around the most available technology of the time, chest radiography. While annual chest radiography alone and more-intensive annual chest radiography and cytologic sputum analysis resulted in more cancers being detected, no mortality benefit resulted from this screening method.2,3 Thus Answers B and D are not correct.
The next lung-cancer screening technology tested was CT scanning. Early data demonstrated mixed results—a high rate of abnormalities, many of which should be eminently treatable stage I tumors, accompanied by problematically high rates of false-positive results.2 And, the early studies did not include a comparison group or mortality data.
Low-Dose CT vs Radiography
Finally, the National Cancer Institute-funded National Lung Screening Trial (NLST) compared annual low-dose CT scanning (with its lower radiation exposure) with annual chest radiography for lung cancer screening.2 The primary outcome was lung cancer mortality, with important secondary outcomes of all-cause mortality and stage distribution of lung cancers found (a reasonable surrogate for treatability).
The NLST researchers recruited a large number of patients—53,454 in all. High risk was defined as individuals aged 55 to 74 years with a 30 or more pack-year history of smoking tobacco, or, if a former smoker, having quit within the last 15 years; or individuals aged 50 years and older with a 20 or more pack-year smoking history with at least one additional risk factor such as family history, prior significant lung disease, or other lung cancer carcinogen exposure.
The results showed the efficacy of this scheme such that the study was stopped early. A statistically significant 20% relative risk reduction (427 lung cancer deaths among the 1865 patients in the CT group vs 503 deaths in the 1991 patients in the radiography group) and a 6.7% decrease in all-cause mortality were demonstrated in the CT group. The study also showed that 320 patients needed to be screened for 3 years to prevent one lung cancer death over the next 6.5 years.2
Consequently, the US Preventive Services Task Force’s current review of screening for lung cancer suggests as a relatively strong “B” recommendation that clinicians offer low-dose CT scanning for the high-risk groups defined in the NLST.4,5 Thus, Answers A and E are not correct using the above definitions, and Answer C is the best answer and explanation to give to the patient and his daughter described above.
The 60-year-old patient in this case opted to undergo screening with annual low-dose CT scanning. He has completely stopped smoking, and his first 2 CT scans were negative for lung cancer.
Ronald Rubin, MD, is a professor of medicine at the Temple University School of Medicine and is chief of clinical hematology in the Department of Medicine at Temple University Hospital in Philadelphia, Pennsylvania.
Trent Wang, DO, is a third-year fellow in the Department of Hematology/Oncology at Fox Chase Cancer Center in Philadelphia, Pennsylvania.
- Marcus PM, Bergstrahl EJ, Fagerstrom RM, et al. Lung cancer mortality in the Mayo Lung Project: impact of extended follow-up. J Natl Cancer Inst. 2000;92(16):1308-1316.
- National Screening Trial Research Team. Reduced lung-cancer mortality with low-dose computed tomographic screening. N Engl J Med. 2011;365(5):395-409.
- Oken MM, Hocking WG, Kvale PA, et al; PLCO Project Team. Screening by chest radiograph and lung cancer mortality: the Prostate, Lung, Colorectal, and Ovarian (PLCO) randomized trial. JAMA. 2011;306(17):1865-1873.
- Humphrey LL, Deffebach M, Pappas M, et al. Screening for lung cancer with low-dose computed tomography: a systematic review to update the U.S. Preventive Services Task Force recommendation. Ann Intern Med. 2013;159(6):411-420.
- NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®): Lung Cancer Screening. Version 2.2016. Fort Washington, PA: National Comprehensive Cancer Network; 2016.