by ecancer reporter Janet Fricker

New draft recommendations from the US Preventive Services Task Force (USPSTF) say that smokers aged between 55 and 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 undergo annual screening for lung cancer with low-dose computed tomography (LDCT).

The recommendation comes in tandem with the online publication of a systematic review in the Annuals of Internal Medicine showing that screening with LDCT can reduce lung cancer and all-cause mortality.

Lung cancer is the leading cause of cancer-related death in the US accounting for almost 27% of all cancer-related deaths. Since early-stage lung cancer is associated with lower mortality than late-stage disease, early detection and treatment may be beneficial.

With approximately 85% of lung cancers attributable to smoking, and 20% of Americans being current smokers, lung cancer is likely to remain a major public health problem for decades to come.

In 2004 the USPSTC judged evidence about the effectiveness of lung cancer screening with chest radiography or LDCT to be insufficient.
In the current study Linda Humphrey and colleagues set out to update the 2004 recommendation by undertaking a review.

The authors identified seven randomized controlled studies that reported results of LDCT screening but limited their review to the effectiveness of three high quality trials that reported results in the intervention and control groups.

One of the studies was the National Lung Screening Trial (NLST) that compared three annual LDCT scans with three annual single view posterior-anterior chest radiographs.

Results showed that LDCT when compared to chest X-ray reduced lung cancer mortality by 20% and all-cause mortality by 6.7%.

The reported number needed to screen to prevent one lung cancer death was 320 among participants who completed one screening. The authors identified two other fair quality trials – one conducted in a high-risk population suggesting benefit, and one conducted in a lower risk population that did not show benefit and suggested harm.

The number needed to treat to prevent one lung cancer death of 320, the authors conclude, compared favourably with 1339 for breast cancer and 817 for colon cancer. “Given the high number of current and former smokers in the population at risk for lung cancer, identifying and treating early-stage lung cancer with screening will hopefully clarify the balance of benefits and harms associated with screening.
In addition, more work in public health to reduce smoking remains the most important approach to reducing morbidity and mortality from lung cancer,” they write.

If LDCT screening becomes routine, they add, the risk for harm should be measured and methods to limit it should be identified.
“It is also important to continue to evaluate the psychosocial consequences in patients who undergo screening, because psychological responses to screening and abnormal or negative results may differ between patients participating in research studies and the general population,” they write.

An area of concern, they add, is that the trials suggested that screening had no impact on encouraging smokers to quit or cut down on tobacco use.
The draft recommendation from USPSTF carries a B grade, which is significant since preventive tests with an A or B grade require Medicare, other federal health programs and private insurers to cover the costs within a year after the guideline is adopted.

The Task Force has invited public comment on its draft recommendation until August 26.

Reference

L Humphrey, M Deffebach, M Pappas, et al. Screening for Lung Cancer with Low Dose Computed Tomography: A Systematic Review to Update the U.S. Preventive Services Task Force Recommendation. Annuals of Internal Medicine doi:10.7326/0003-4819-159-6-201309170-