Researchers at the Mayo Clinic recently identified that a decline in smoking rates may indicate that people suitable for CT-screening are not meeting eligibility criteria. The research titled “Trends in the Proportion of Patients With Lung Cancer Meeting Screening Criteria,” is published in JAMA, The Journal of the American Medical Association.
“As smokers quit earlier and stay off cigarettes longer, fewer are eligible for CT screening, which has been proven effective in saving lives,” said Ping Yang, M.D., Ph.D., an epidemiologist at Mayo Clinic Cancer Center in a recent news release. “Patients who do eventually develop lung cancer are diagnosed at a later stage when treatment can no longer result in a cure.”
Based on the study, results the researchers suggest there is a need for reevaluating screening criteria to detect the proportion of patients who have developed lung cancer. “The existing screening program will become less effective at reducing lung cancer mortality in the general population, if they continue to use the same criteria,” Dr. Yang said.
In their retrospective study conducted from 1984 to 2011, Ping Yang, MD, PhD from the Mayo Clinic and colleagues identified approximately 140,000 residents of Olmsted County in Minnesota. The Rochester Epidemiology Project database was used to detect lung cancer cases. Cases were classified according to the World Health Organization pathology definition. The U.S Preventive Services Task Force criteria was used to determine the number of patients that met CT scan screening. The criteria recommends that CT scan screening should be preformed in adults without history of symptoms, aged between 55 and 80 years that smoke 1 pack a day for 30 years.
Results showed that during the study period, 1,351 subjects developed lung cancer, with a decline in lung cancer patients over the years, but with an increase in the number of patients that quit smoking for more than 15 years. “While more people have quit for a longer period of time, they are still getting lung cancer,” Dr. Yang said “and they make up a larger proportion of newly diagnosed lung cancer patients.”
The number of patients with lung cancer that could have been eligible for CT screening decreased from 57% between 1984-1990 to 43% between 2005–2011. The number of women and men eligible decreased from 52% to 37% and 60% to 50%, respectively.
According to Dr. Yang, this trend means that many patients miss early identification, where treatment is more effective. “That means more patients are going to be diagnosed at a later stage, because they could not take advantage of early detection,” explained Dr. Yang.
She noted that CT screening should be regulated to involve people who have smoked less than a pack every year over 30 years and also to include people who quit smoking for more than 15 years. “We don’t want to penalize people who succeeded in smoking cessation,” she said. Still, some cancer-free smokers continue to smoke, making them suitable for screening.
At the moment CT, scan screening is the only available technology that has been found to save lung cancer patients’ lives, however, this method will be less effective if the criteria is not revised. Dr. Yang further noted that CT-screening eligibility criteria cannot be too broad and there should be awareness of factors such as cost, radiation exposure and overtreatment.
“There are ways to screen at-risk patients while still avoiding false alarms and overtreatment,” concluded Dr. Yang. “Researchers need to discover biological markers, such as genetic or physiological traits, to help them better identify high-risk patients.”