Computer Tomography Lung Cancer Screening Programs

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computer tomography

Lung cancer is the leading cause of cancer death in Canadian men and women, thereby placing a heavy burden on researchers and health-care providers to develop novel preventative and therapeutic interventions. Although lung cancer screening programs using computer tomography (CT) scans, have been shown to reduce mortality rates, whether they can be implemented in a cost-effective manner remains controversial.

 

According to the Canadian Cancer Society, lung cancer is the leading cause of cancer death amongst Canadian men and women. Highly reputed organizations have advocated for lung cancer screening programs, using low-dose computed tomography (CT) scans, in hopes of early detection and therapy initiation, thereby reducing mortality rates. However, many Canadians in Ontario, have raised concerns regarding the cost-effective implementation of lung cancer screening programs. Currently, the United States Preventative Services Task Force (USPSTF) recommends lung cancer screening for current and former smokers that have quit within the last 15 years, aged 55 through 80 who smoked at least 30 pack-years. However, the USPSTF recommendation has failed to account for cost-effectiveness, and most studies that have tried to address the economic cost directly remain inconclusive. A recently published article, in PLoS, demonstrated that limiting lung cancer screening to individuals with a substantial smoking history can be cost-effective and prove beneficial to the Canadian population.

The study utilized the Microsimulation screen analysis (MISCAN) lung model, which simulates each individual’s life history from birth until death in the presence and absence of screening programs. By comparing life history, with and without screening, the MISCAN-Lung can give an estimate of the cost-effectiveness of the screening program itself. The study evaluated 576 potential screening programs, consisting of different criteria, including age to start and stop screening, the screening interval, cumulative smoking exposure, and years since smoking cessation. The gain of one life-year for every $50,000 Canadian dollars spent for screening was defined as being cost-effective, which is similar to previous studies investigating the cost-effectiveness of lung cancer screening programs.

The results demonstrated that annual screening of current and former smokers between the age of 55-75, who smoked >40 pack-years, cost $41,138 Canadian dollars per life-year gained. Furthermore, the screening program could reduce lung cancer mortality in the overall population by approximately 9%, thereby preventing 251 lung cancer deaths in the population. However, this screening program would also lead to cases of over-diagnoses, resulting from false positives, surgeries for benign diseases, and biopsies/bronchoscopies. Other screening programs that began screening individuals at an older age had a lower cost, but were also associated with a smaller number of life-years gained. The results established that screening programs that focused heavily on individuals with a long smoking history were more cost-effective. Finally, it was shown that although biennial (every two years) screening had lower costs, compared with annual screening, the life-years gained were also substantially lower. Instead, annual screening proved to be much more cost-effective, where you have a larger cost but gain significantly more life-years.

In conclusion, the simulation study demonstrated that lung cancer screening programs can be implemented in a cost-effective manner, given strict parameters. Focusing on individuals at higher risk of developing cancer, like those that have a significant history of smoking, can be cost-effective and beneficial. Furthermore, the benefits of annual lung cancer screening outweigh the additional costs, when compared to biennial screening. Moving forward, other screening strategies could also be investigated to develop an even more cost-effective screening program. It is important to note, however, that the current study defined cost-effectiveness as being $50,000 Canadian dollars per life-year gained. Different countries will have to define their own thresholds and therefore a cost-effective screening strategy in Canada may not necessarily be appropriate for another country.

 

Written By: Haisam Shah, BSc