For the first time, there’s evidence that screening smokers may save them dying of lung cancer.
The U.S. Preventive Services Task Force (USPSTF) , a government-based panel of experts, released a draft recommendation that smokers between the ages of 55 to 80 who have a history of smoking a pack a day for 30 years or more, as well as those who have quit within the last 15 years, should get low dose CT scans of their lungs to look for possible tumors. Smoking accounts for about 85% of lung cancer, which is among the leading causes of cancer deaths in the U.S. each year.
The advice comes after the USPSTF determined in two previous reviews that there was not enough evidence to support the annual screenings. But new studies support the fact that the small risk of radiation exposure from the low dose scans was outweighed by the benefits of detecting abnormal growths early and intervening with treatments. The National Lung Screening Trial (NLST) study by the American College of Radiology Imaging Network (ACRIN), for example, found that low-dose CT scans reduced lung cancer deaths among former smokers as well as current smokers aged 55 to 74 by 20% compared to X-rays. Another study, published in the journal Cancer found that such CT screening could prevent up to 12,000 lung cancer deaths each year, which could also significantly lower health costs associated with the disease.
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When the NLST results were released in 2011, the American College of Radiology issued a statement pledging to create better guidelines, standards, and staffing changes to support more widespread screening. “Evidence-based infrastructure will have to be put in place nationwide to ensure that patients have access to uniform, quality care and a similar life-saving benefit from these exams as demonstrated in the NLST,” the college wrote.
In recent years, the USPSTF has been issuing controversial advice concerning cancer screening, based on updated evaluations of the data. In 2009, the task force recommended that most women delay mammogram screening for breast cancer until age 50, a full decade later than previous guidelines. And last year, the panel found that widespread screening with the prostate specific antigen (PSA) test was not contributing to fewer deaths from prostate cancer, and advised men to skip the test altogether.
With the current lung cancer recommendation, the Task Force joins organizations such as the American College of Chest Physicians, American Society of Clinical Oncology, the American Thoracic Society, the National Comprehensive Cancer Network (NCCN) and the American Lung Association, which have been recommending lung cancer screening with low dose CT scans for those at-risk since May 2012.
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The proposed recommendation is available for public comment until August 26, after which the task force will make any suggested modifications and issue its final guidelines. At that point, insurance companies will have to reimburse annual lung cancer screenings for the appropriate populations, as designated under the the Affordable Care Act.
But with more screening, some experts say there will be confusion over the CT’s false positive and false negative readings. The test misses about 20% of lung cancers, and can falsely detect tumors at high rates as well, which means more people may be diagnosed with cancer who might not have malignant growths. “Overdiagnosis is guaranteed,” Dr. Peter Bach, the director of Memorial Sloan-Kettering Cancer Center’s Center for Health Policy and Outcomes told Reuters about the new recommendation.
Task Force member Dr. Michael LeFevre of the University of Missouri in Columbia says overdiagnosis is inevitable in screening in general, and in cancer screening specifically. The panel estimates that around 3% to 4% of the cancers that are detected through screening may never have caused a person a problem in their lifetime. “By contrast, from a Task Force perspective, back when we made our last recommendation about mammography, we were looking at a 10% overdiagnosis estimate,” he says. “We consider 3% to 4% pretty low considering the devastating consequences of lung cancer in the United States today.”
Screening, however, cannot substitute for the protective effect of quitting smoking, says the task force, and the panel stresses that the most effective way to lower deaths from lung cancer is to reduce smoking rates.