We know that catching lung cancer at an early stage dramatically increases the chances of survival. Over the last 20 years, through the dogged efforts of leading researchers in the field, a veritable mountain of evidence has been compiled to prove that we can use CT screening to reduce mortality in lung cancer patients. In the early 1990s, researchers at Cornell University Medical Center in New York City formed the Early Lung Cancer Action Program (ELCAP), designed to evaluate the effectiveness of CT screening for lung cancer in heavy smokers.
In the earliest trial, they screened 1000 asymptomatic smokers with low-dose chest CT scan and found that over 80% of the lung cancers found were early stage (stage I) (Lancet 1999). Remember that, historically, only 15% of newly diagnosed lung cancer patients have had localized disease. They also found that low-dose chest CT found 4 times more cancers than plain chest x-rays.
After a followup statewide study (NY-ELCAP) that corroborated the original results, ELCAP expanded globally to become the International ELCAP group (I-ELCAP).
The I-ELCAP study group is now looking into the effectiveness of low-dose chest CT in never-smokers with significant secondhand smoke exposure, an important area of research. They are actively enrolling patients in this FAMRI trial.
Taken directly from the I-ELCAP summary of its own work:
Numerous publications document the findings of the I-ELCAP members’ work. Among these findings as already stated above:
The ELCAP studies were a landmark in lung cancer research. All of the ELCAP participants received both a low-dose chest CT and a chest x-ray. Of the patients who were eventually diagnosed with lung cancer, the researchers looked to see if their low dose chest CT or their chest X-rays caught the cancer. What remained was to design a randomized controlled clinical trial where patients were randomized to either an annual low-dose chest CT or an annual chest X-ray, and to see if one of the groups had its mortality improved by the screening test.
The capstone of lung cancer CT screening research was published in 2011 in the New England Journal of Medicine the results of the National Lung Screening Trial (NLST). The NLST enrolled almost 54,000 heavy smokers aged 55-74 with 30 pack-years or more of smoking* at 33 medical centers in the United States. Half of the patients underwent yearly low dose chest CT scan and the other half underwent yearly chest X-ray. The trial was stopped early because of dramatic results showing the clear benefit of low dose chest CT.
Mortality in the low-dose chest CT group was 20% lower than in the chest X-ray group. This is a dramatic reduction. Consider that in the trial the alternative to the chest CT was a chest X-ray, rather than no imaging at all. One would expect the mortality benefit to be much larger when compared to the average smoker who is not screened at all with imaging. Additionally, the NLST only performed 3 scans, separated a year apart (one at the start, the second after a year, and the last at the end of 2 years). One would expect a greater mortality benefit to continue to accrue with continued yearly screening. So the 20% mortality benefit may in fact represent a “floor” to the expected benefit to patients who undergo annual CT screening in clinical practice.
To summarize, annual low-dose chest CT leads to early diagnosis of lung cancer in the majority of cases, compares favorably in cost and benefit to other interventions, and provides at least a 20% mortality benefit to heavy smokers.
*To calculate pack-years, multiply the number of years the patient smoked by the average number of packs of cigarettes smoked. A 2 pack a day smoker who smoked for 20 years is a 40 pack-year smoker.
There is widespread consensus on the evidence and benefit of lung cancer screening. There are contrarian voices to this mountain of evidence, but they are without merit.
The Lung Cancer Alliance, Society of Thoracic Surgeons, American College of Radiology (ACR), American Thoracic Society (ATS), and American Cancer Society (ACS) / Cancer Action Network all support lung cancer screening; please see their joint statement.
So do the American Society for Clinical Oncology (ASCO) and the American College of Chest Physicians (ACCP); please see joint statement
So does the American Medical Association (AMA); see statement
The United States Preventive Services Task Force (USPSTF) agreed, issuing in 2014 a class B recommendation to cover screening in patients 55-80 with 30 pack-years of smoking and who had not quit more than 15 years earlier. USPSTF Recommendation
Centers for Medicare and Medicaid Services (CMS) preliminarily agreed as well in late 2014, limiting the age range to 55-74 in keeping with NLST eligibility rules. CMS also included several reasonable requirements surrounding the management and ordering of LDCT in order to promote responsible lung cancer screening methods. Proposed Decision Memo CAG-00439N
So while there may be a few editorialists who for unknown reason use their bully pulpits to question screening, recognize that the preponderance of evidence and the professional societies who know the field best all point to the benefit and importance of lung cancer screening.