Which criteria should be used to chose individuals for lung cancer screening? It is not clear which individuals at risk for lung cancer should be screened with computer tomography (CT).
A recent study, lead by Dr. Martin C. Tammemagi from Brock University, Canada, and published in Plos Medicine, attempted to identify a threshold that could serve as a reference to select individuals for lung cancer screening, comparing its efficiency and reliability with the United States Preventive Services Task Force (USPSTF) criteria for the same purpose. Furthermore, researchers wanted to determine if people who never smoked should also be screened.
Lung cancer is the number one cause of death, worldwide, and cancer-related symptoms often include breathlessness and persistent cough. It occurs when genetic changes happen to cells allowing them to grow uncontrollably and to migrate to several different parts of the body, the so called metastasis.
These changes are often promoted due to cigarette smoke exposure. When diagnosed early, lung cancer can be surgically removed. In stage II cases, when the disease already spread into lymph nodes, surgery plus radio or chemotherapy is required. Advanced stage III cancers present in the whole chest or stage IV spread throughout the body, are treated with chemo or radiotherapy because at this point, surgery is no longer helpful. Usually, lung cancer is detected in advanced stages and less than 17% of patients diagnosed survive for more than 5 years.
The US Preventive Services Task Force (USPSTF) suggests people between 55-80 years old, that have smoked a pack of cigarettes per day for more than 30 years, along with those who quit less that 15 years ago, should be annually screened through CT. Other experts say that risks can be calculated through statistical models that take into account several personal characteristics.
In this study, scientist evaluated the PLCOm2012 model – a prediction model based on the incidence of lung cancer in smokers that enrolled the United States Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO). Data from the US National Lung Screening Trial (NLST) and the PLCO screening trial were used to assess the efficiency of the PLCOm2012 model, comparing it to the USPSTF criteria to identify patients liable for screening.
The research team found that through the NLST data, a ≥0.0151 threshold in the PLCOm2012 model could improve the efficiency of the selective process. Further, the PLCOm2012 improved sensitivity and specificity when it came to choosing screeners, in comparison to the UPSTF criteria.
In their study, the authors suggest that screening may be extended to those who stopped smoking for more than 15 years. Furthermore, smokers between the ages of 65 and 80 can also benefit from screening.
“Use of the PLCOm2012 risk ≥0.0151 threshold for screening should result in more efficient and cost-effective screening programs. This should make lung cancer screening more attractive for policy-makers and more affordable for health systems”, the authors conclude in their study.
