MODEL TO CHOOSE PATIENTS FOR LUNG CANCER SCREENING 

NEW YORK (Reuters Health) Feb 20 - Selecting people for lung cancer screening using a modified model based on the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial proved more efficient and sensitive than using criteria from the National Lung Screening Trial (NLST), researchers reported this week.

Use of the modified PLCO model to select appropriate candidates for lung screening programs "could potentially be an effective method leading to improved cost-effectiveness of screening with additional deaths from lung cancer prevented," they conclude.

For institutions planning on implementing a lung cancer screening program for high risk individuals, "using elevated risk as predicted by a proven lung cancer risk prediction model is the method of choice for selecting candidates for screening, compared to using the NLST smoking criteria," Dr. Martin C. Tammemagi an epidemiologist at Brock University, St. Catherines, Ontario, Canada, wrote in an email to Reuters Health.

The NLST published in 2011 showed that lung-cancer screening with the use of low-dose computed tomography (CT) resulted in a 20% reduction in mortality from lung cancer.

Many organizations that now screen for lung cancer use NLST criteria, which include an age between 55 and 74 years, a history of smoking of at least 30 pack-years, a period of less than 15 years since cessation of smoking, or some variant of these criteria. These selection criteria are intended to increase the yield of lung cancers, but they exclude many known risk factors for lung cancer, Dr. Tammemagi and colleagues say.

"Use of an accurate model that incorporates additional risk factors to select persons for screening may identify more persons who have lung cancer or in whom lung cancer will develop, they add.

They previously developed and validated a lung cancer risk-prediction model based on data from former and current smokers in the PLCO cancer screening trial.

Predictors in the PLCO model include age, level of education, body-mass index (BMI), family history of lung cancer, chronic obstructive pulmonary disease (COPD), chest radiography in the previous three years, smoking status (current smoker vs. former smoker), history of cigarette smoking in pack-years, duration of smoking, and quit time.

In the PLCO model, risks are based on a median follow-up of 9.2 years, which exceeds the six-year follow-up in the NLST, making a comparison difficult.

As reported online February 20 in the New England Journal of Medicine, Dr. Tammemagi and colleagues modified and updated the PLCO model to make it directly applicable to NLST data.

Their analyses included 73,618 smokers in the PLCO study and 51,033 NLST participants.

For the modified PLCO model, the area under the curve (AUC) was 0.803 in the development data set and 0.797 in the validation data set. An AUC in this range "may be of value in providing individual-level information and in population-level screening programs," the researchers say.

As compared with NLST criteria, the modified PLCO model had improved sensitivity (83.0% vs 71.1%, p<0 .001="" 3.4="" 62.7="" and="" loss="" of="" p="" positive="" predictive="" researchers="" respectively="" say.="" specificity="" the="" value="" vs="" without="">

Overall, the modified PLCO model identified 81 more of the 678 lung cancers (11.9%) than did the NLST criteria (41.3% fewer lung cancers were missed).

Dr. Tammemagi told Reuters Health he's already been approached by several groups who plan to implement the model for enrolling individuals into lung screening programs or research studies. "With application of the prediction model and suitable follow-up we should develop a sense of how well it works in a few years," he said.

Dr. Tammemagi also told Reuters Health, "Currently, the Pan-Canadian Early Detection of Lung Cancer Study has enrolled individuals on the bases of elevated risk according to a prototype of the current lung cancer risk prediction model. In that study 113 cancers have been detected in 2537 enrollees in an average of three years of follow-up. This 4.5% yield of lung cancers is much higher than observed in the National Lung Screening Trial and is very close to that predicted by the model. The Canadian study corroborates the findings we reported in the NEJM article. We expect to publish Canadian study findings shortly."

SOURCE: http://bit.ly/Yn8xsf

N Engl J Med 2013;368:728-736.