(RxWiki News) Lung cancer can be detected early using CT scans. But when doctors find nodules on these CT scans, it can be hard for them to tell which ones will likely turn out to be cancerous.
A new risk calculator software can accurately predict, nine out of 10 times, the risk of a nodule detected on a CT scan being cancerous, says a new study.
According to the study, the newly developed prediction tool may lead to fewer follow-up diagnostic tests and biopsies (removal of tissue sample) for patients whose CT scans show nodules, while continuing to catch lung cancer at an early stage.
"Ask your doctor about CT scans for lung cancer screening."
This study was conducted by Stephen Lam, MD, professor of medicine at the University of British Columbia, along with colleagues.
The aim of the study was to find out how to predict whether lung nodules detected via computerized tomography (CT) screening for lung cancer will be found to be malignant (cancerous) on follow-up.
Recently, a large study called the US National Lung Screening Trial (2011) found that using low-dose CT scans to screen high-risk individuals, especially smokers, for lung cancer led to a 20 percent reduction in lung cancer deaths.
However, one concern with CT scans is that many people have nodules on their CT scans. It is hard to tell which nodules detected on CT scans are more likely to be cancerous. This means that patients may be subjected to unnecessary and painful tests and procedures, including biopsies.
If doctors could tell which nodules were more likely to be cancerous, they could recommend further tests to patients who have a higher likelihood of having lung cancer.
"Reducing the number of needless tests and increasing rapid, intensive diagnostic workups in individuals with high-risk nodules are major goals of the model," said Martin C. Tammemagi, PhD, one of the study co-authors.
During the current study, the researchers examined two different Canadian studies with a total of 12,029 lung cancer nodules found on the CT scans of 2,961 current and former smokers aged 50 to 75 years.
In one study, participants were followed for an average of three years, and the other study followed participants for an average of 8.5 years.
In the first study, 1,871 people had 7,008 nodules, of which 102 were malignant. In the second study, 1,090 people had 5,021 nodules, of which 42 were malignant. Among those who had nodules on their CT scans, the rates of cancer in two studies were 5.5 percent and 3.7 percent, respectively.
Using this data and the characteristics of the participants in the two studies, the researchers developed a way to predict which nodules were likely to be cancerous.
According to the researchers, older age, female sex, family history of lung cancer, larger nodule size, fewer nodules, nodules in the upper lobe, nodules that were partly solid and nodules that had pointy edges were good predictors of cancer. Emphysema, which is a condition where the lung tissue gets destroyed slowly, leading to breathing trouble, was also a predictor.
The model developed by the researchers accurately predicted cancer in a majority of cases, even in nodules that were smaller than 10 millimeters in size.
"An accurate and practical model that can predict the probability that a lung nodule is malignant and that can be used to guide clinical decision making will reduce costs and the risk of morbidity and mortality in screening programs," the researchers wrote.
The results of this study were published September 5 in The New England Journal of Medicine.
The study received funding from the TFRI, the research arm of the Terry Fox Foundation, and the Canadian Partnership Against Cancer.