Researchers led by Mattias Johansson and Hilary Robbins, scientists at IARC and senior authors of the study, started with more than 1,200 proteins they believed might be implicated in lung cancer. They winnowed them down to 13 after analyzing data from thousands of smokers and former smokers in an IARC database who provided blood samples before they knew if they would develop cancer, and who were followed for three years to see if they did. Some of the proteins are known to be involved in lung cancer, while others are new, says Johansson, although the study was not designed to delve deeper into the what those proteins do. In a previous study, the team described the iterative process of isolating the most meaningful blood markers for the test.
Johansson and Robbins say the goal of the blood test is not to replace CT scans, which are effective but expensive and may expose people to unnecessary amounts of radiation if they are used broadly in a large population. “This test allows us to identify some of those who actually have high risk,” Johansson says. “This is really about screening in a smarter way, to focus on those likely to benefit, and avoid screening people who don’t need it.”