There was concern that cancers diagnosed in routine screening were less aggressive than those found in routine practice.
Lung cancers found through annual CT screening are similar to those found in routine practice, both in volume doubling time and cell-type distribution, said researchers in a report from the International Early Lung Cancer Action Program (I-ELCAP), published online in the journal Radiology.
I-ELCAP principal investigator Claudia I. Henschke, PhD, MD, professor of radiology at Mount Sinai School of Medicine in New York, explained that there was concern that cancers diagnosed in screening were less aggressive than those found in routine practice.
To determine if there were differences in growth rates, researchers from Mount Sinai School of Medicine identified and analyzed 111 instances of first primary lung cancer (88 clinical Stage I) diagnosed either through screening or between rounds after a negative result of prior screening seven to 18 months earlier.
According to their findings, the median volume doubling time (VDT) was 98 days (interquartile range, 108). For half the cancers, it was less than 100 days and for three (3 percent), it was more than 400 days.
Subsolid lung cancers had significantly longer VDTs than solid nodule cancers. The most frequently identified cell type was adenocarcinoma (50 percent), followed by squamous cell carcinoma (19 percent), small cell carcinoma (19 percent) and others (12 percent).
Lung cancers identified in clinical practice have a reported VDT range from 20 to 360 days and findings from a recent systematic medical literature review identified VDT of 135 days for non-small-cell lung cancers diagnosed in the absence of screening.
“This study shows that the cell types of cancer diagnosed in annual rounds of screening, as well as their growth rates, are quite similar to those that are found in clinical practice, where it is well understood that lung cancer is highly lethal,” said Henschke.