The conclusion of the National Lung Screening Trial (NLST) in November 2011 has created a new patient population—high-risk current and former smokers potentially eligible for CT screening. A clinical crossroads published March 20 in Journal of the American Medical Association addressed key points to consider in the informed decision-making process, remaining questions and the potential benefit of software, such as computer-aided detection and volumetric measurement tools, in CT screening.
The JAMA article focused on a 64-year old female former smoker who had accumulated 30 pack-years before quitting when her father died from lung cancer. The patient underwent three rounds of screening CT in the NLST; during the initial exam numerous micronodules smaller than 4 mm were detected. They did not progress in the next two exams.
Phillip M. Boiselle, MD, reviewed salient points in the question of whether or not the patient, who can afford to pay out of pocket, should continue screening.
The knowns are simple, according to Boiselle. NLST demonstrated that CT screening reduces lung cancer mortality by 20 percent, and it is safe.
Upcoming publications from NLST will answer other questions, including:
- How does CT screening influence utilization of medical resources?
- What is the added monetary cost due to CT screening?
- How does the process of CT screening influence participants’ quality of life and smoking habits?
However, other questions require additional data. These are:
- Will other populations at risk of lung cancer benefit from CT screening?
- Will less frequent screening regimens be equally effective as annual screening?
- How long should screening continue?
- Will the NLST results be reproducible in community hospital settings?
Boiselle also enumerated risks associated with CT screening. Nearly 40 percent of participants had at least one positive exam. Although most of these were followed via CT, a handful required invasive testing. Thus, there is potential for unnecessary testing and additional costs. Overdiagnosis, which has been estimated to occur in 25 percent of chest x-ray exams for lung cancer, also presents a risk, according to Boiselle.
Equity and reimbursement represent larger health system issues. “Until broad coverage for CT screening is available by insurers and other payers, one of the greatest barriers of CT screening is the ability to provide it to individuals at risk across all socioeconomic strata.”
Regarding the specific patient in the scenario, her successful smoking cessation now would disqualify her from NLST entry, so guidelines based on NLST criteria, such as those published by the American Cancer Society, would not recommend screening. However, National Comprehensive Cancer Network guidelines consider the patient’s history appropriate for screening.
Boiselle recommended screening after the patient and her physician weigh the risks and benefits of screening, and also espoused screening at an academic center with access to a multidisciplinary team of experts.
Finally, he referred to interobserver variability in the detection of large nodules and suggested computer-aided detection and volumetric software may improve reader agreement in the future.
For more about CT screening, please read, "Can imaging practices provide multidisciplinary lung cancer screening?" and "Getting lung cancer screening right in the community setting."