SAN FRANCISCO – Patients aged 55-74 years who have at least a 30 pack-year smoking history should be offered annual low-dose CT lung cancer screening, even if they have quit within the past 15 years, according to a systematic review published online May 20 in JAMA.
The review forms the basis of the new lung cancer screening clinical practice guidelines from the American College of Chest Physicians and the American Society of Clinical Oncology. The recommendations are based largely on the 53,454-patient, randomized NLST (National Lung Screening Trial), which found that for every 1,000 high-risk smokers, three rounds of annual CT screening saved approximately three lives over about 7 years, which is comparable, at least, to the absolute benefit of screening mammographies in older women (N. Engl. J. Med. 2011;365:395-409).
The risks – including misdiagnosis and unnecessary surgery – and potential benefits should be explained to patients before they opt for screening. "People need to know" that "19 out of 20 positive results are going to be false positive. A positive screen does not equal a diagnosis of lung cancer," said coauthor Dr. Michael K. Gould, assistant director for health services research at Kaiser Permanente of Southern California, Pasadena.
In addition, "CT screening should not be performed" in smokers and ex-smokers who fall outside of the high-risk group, or in those with severe comorbidities that limit life expectancy or preclude treatment, according to the guidelines (JAMA 2012 May 20 [doi:10.1001/jama.2012.5521]).
The risks and benefits of screening are just "too close to call" for those patients, said lead author Dr. Peter Bach, director of the center for health policy and outcomes at Memorial Sloan-Kettering Cancer Center in New York.
After an extensive literature review, the researchers included eight randomized trials and 13 cohort studies in its final analysis. Although they are confident that screening benefits high-risk patients – based mostly on the NLST, with some added input from smaller trials – they are also concerned about the lack of data on the potential harms of screening, which led to the recommendation to offer screening only to high-risk patients, Dr. Bach said.
Overall, the lack of additional research led both recommendations to be characterized as "weak" under the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system.
The impact of screening even high-risk patients "on smoking cessation, quality of life, and cost-effectiveness is really quite unclear. We don’t know in any sense what the frequency should be or the duration," Dr. Bach said.
Also unclear is how screening will play out in settings less rigorous than the academic centers where the NLST was conducted. Patient compliance with screening at those centers was 90%, adverse events were rare, and subsequent diagnostic work-ups and interventions were available.
To mitigate potential problems, the guidelines recommend that screening be done in similar multidisciplinary settings.
The authors also call for a screening registry "that records each patient’s experience [to] help us develop a quality measurement system similar to mammography screening that could maximize the benefits and minimize the harm for individuals who undergo screening," Dr. Bach said.
A supplement to the JAMA article includes a section entitled "Components of a Conversation About CT Screening," which addresses how to talk with patients about these issues.
The American Thoracic Society has endorsed the guidelines.
Dr. Bach reported that he has received speaking fees from Genentech. Coauthors reported ties to pharmaceutical companies such as Oncimmune and governmental agencies such as the National Cancer Institute. Dr. Gould and Dr. Bauchner said they have no relevant disclosures.