Scientists have come closer to developing new screening tests that could detect lung cancer, the leading cancer killer in the world, during its earliest stages, according to preliminary studies to be presented this week at a medical meeting in San Diego.

Tissue samples from healthy smokers were studied by researchers at Weill Cornell Medical College in New York City who were able to pinpoint precancerous mutations in the cells lining the airways leading to the lungs.

“We found that the earliest molecular changes related to lung cancer are present in the airway epithelium of healthy smokers who do not have any detectable microscopic abnormalities in the lung tissue,” Dr. Renat Shaykhiev, study author and assistant professor of genetic medicine at Weill Cornell, told USA Today.

Shaykiev hopes that the findings “may lead to the development of novel strategies to prevent lung cancer development at the very early stages, before the development of clinically detectable cancer.”

Researchers at the University of Texas MD Anderson Cancer Center in Houston conducted parallel research in which they developed a blood test that could isolate specific genetic mutations of tumor cells, as small as three cells.

“We have developed an extremely sensitive test that could be able to detect mutations present in circulating tumor cells, and we are hoping that from their characterization we would be able to understand diagnostic, prognostic, and predictive markers,” researcher Heidi Erickson said in a news release for the American Association for Cancer Research.

“By being able to collect a blood sample from a patient instead of having to do a biopsy, we’ll have an opportunity to monitor the patient throughout treatment in an easier way,” she said.

In addition, researchers are also in the midst of developing a system of detecting lung cancer in its earliest stages based on proteins in the blood along with organic compounds in the breath.

According to the American Cancer Society, an estimated one out of every 14 men and women in the U.S. will be diagnosed with lung cancer.