NCCN Reaffirms Lung Cancer Screening of Heavy Smokers

The benefits of routine lung cancer screening in high-risk individuals outweigh the potential risks, according to members of a National Comprehensive Cancer Network guidelines panel that recommended low-dose helical CT screening of two high-risk groups.

Mary E. Reid, Ph.D., of the Roswell Park Cancer Institute in Buffalo, N.Y., acknowledged the burdens – in particular, the cost and requisite resource utilization – associated with following all high-risk patients who screen positive. But, she said, "the evidence [in favor of] the recommendations is really strong and supports their implementation."

Dr. Mary E. Reid

Lung cancer, she noted, is the only one of the top four deadliest cancers (lung, prostate, breast, and colorectal) that is not currently subject to routine screening.

Dr. Reid and colleagues on the National Comprehensive Cancer Network (NCCN) Guidelines Panel for Lung Cancer Screening presented the update at the NCCN annual conference March 14-18 in Hollywood, Fla. It had been issued in October 2011 and followed a New England Journal of Medicine report that low-dose CT screening of heavy smokers reduced lung cancer mortality by 20%, compared with annual chest x-rays, in the National Lung Screening Trial (NLST).

The revised guidelines recommend annual low-dose helical CT screening for the following two groups of high-risk individuals:

• Those aged 55-74 years with a minimum smoking history of 30 pack-years who either are current smokers or quit within the past 15 years.

• Those aged 50 years or older with a minimum smoking history of 20 pack-years plus one additional lung cancer risk factor, excluding secondhand smoke exposure.

Evidence from the randomized, controlled NLST suggests that early detection via screening reduced lung-cancer specific mortality in the former risk group, which characterizes the NLST patient population. Specifically, 1 in 100 high-risk individuals who were enrolled in the study screened positive on their first low-dose CT exam, and one life was saved for every 320 high-risk individuals screened over 2 years (three screens) ( N. Engl. J. Med. 2011;365:395-409 ). The NCCN recommendation for this group is category 1, the highest level.

The recommendation for annual screening in the second high-risk group is based on less-robust evidence and a nonuniform consensus of the NCCN panel members, Dr. Reid said. As such, it is a less-emphatic category 2B recommendation.

The NCCN screening recommendations have been deemed by some experts to be premature in the absence of cost-efficacy analysis, particularly because of the high false-positive rates observed in both the CT group (96.4%) and the radiography group (94.5%), as well as the potentially harmful effects of radiation exposure associated with low-dose CT screening.

Despite the favorable outcome of their study, the NLST authors stressed the need for rigorous cost-effectiveness analyses before the crafting of public policy recommendations. "The reductions in lung-cancer mortality must be weighed against the harms from positive screening results and overdiagnosis, as well as the costs," they wrote. "The cost component of low-dose CT screening includes not only the screening examination itself but also the diagnostic follow-up and treatment."

In addition to recommending appropriate candidates for routine screening and the proposed frequency of the scans, the new NCCN guidelines outline lung cancer risk factors, address the risks and benefits of screening as well as screening accuracy, and offer an algorithm for the evaluation and follow-up of positive screens.

Specifically, the guidelines recommend the following:

• Basing the frequency of low-dose CT in high-risk patients on the size and status (solid, nonsolid, part-solid, ground-glass, ground-glass opacity) of the nodule on baseline CT.

• Excising all nodules that increase in size or become solid or part-solid during follow-up.

• Considering PET with CT for nodules 8 mm or larger at baseline.

• Performing biopsy or excision of nodules that are suspicious for lung cancer, based on PET with CT findings.

• Reexamining within 1 month solid endobronchial nodules with low-dose CT immediately after vigorous coughing.

• Counseling smokers to quit.

The NCCN is the first professional organization to recommend routine low-dose CT screening for individuals who are considered to be at high-risk for lung cancer, according to Dr. Reid. Last summer, the International Association for the Study of Lung Cancer issued a call for physicians to discuss lung cancer screening with patients who match the high-risk smoking history of those enrolled in the NSLT.

Dr. Reid disclosed no financial conflicts of interest. Disclosures of the NCCN Guidelines Panel for Lung Cancer Screening are online.