A Chinese research team has developed the world's first blood-based diagnostic kit that can tell whether lung nodules are benign or cancerous, including very small nodules that are often difficult to assess using existing methods. Researchers say the breakthrough could significantly improve early detection of lung cancer.

Lung cancer is the deadliest cancer in China, largely because many cases are discovered at an advanced stage. Early symptoms are often mild or absent, delaying diagnosis and treatment.

Low-dose CT scans are widely used to screen people at high risk, such as smokers or those with a family history of lung cancer. However, CT scans can only detect nodules and cannot determine whether they are malignant. Patients must undergo repeated follow-up scans, and studies show that fewer than 30 percent are able to comply with long-term monitoring.

"Distinguishing benign from malignant nodules is the key to achieving earlier lung cancer diagnosis and lowering mortality," said Hu Hai, a professor at the Chinese Academy of Sciences' Hangzhou Institute of Medicine and vice-president of Zhejiang Cancer Hospital, who leads the research team.

To solve this problem, the team spent about 10 years studying tumor autoantibodies — immune system signals that can appear in the blood at a very early stage of cancer, even when the number of cancer cells is still small.

Using techniques from synthetic biology and artificial intelligence, researchers analyzed complex blood samples and screened more than 400 proteins linked to early stage lung cancer. From these, they identified 13 biomarkers that are most useful for diagnosis. Eight of the biomarker combinations are newly discovered and perform significantly better than existing clinical standards in China and overseas, according to the team.

The researchers also tackled manufacturing challenges that have restricted similar tests, such as inconsistent results between production batches and short shelf life. By using customized protein tags and freeze-drying technology, they extended the kit's shelf life to 12 months under refrigeration. All core raw materials are produced domestically, ensuring a stable supply and consistent quality.

The kit was tested in clinical trials at leading hospitals, including Tongji Hospital of Huazhong University of Science and Technology's Tongji Medical College and Beijing Chest Hospital. The trials enrolled 1,463 patients with lung nodules, including 794 lung cancer cases, of which 462 were early-stage cancers.

Results showed the kit detected more than 65 percent of early-stage lung cancer cases, with accuracy significantly higher than traditional diagnostic methods. For small nodules that are often difficult to assess using low-dose CT scans alone, the test increased diagnostic accuracy to more than 85 percent.

The blood test costs about 1,000 yuan ($144) and requires only 2 milliliters of blood. Researchers say this avoids the risks associated with invasive biopsies and makes testing easier for elderly or physically frail patients, while also reducing follow-up costs.

"This marks a major step forward in early lung cancer diagnosis in China, shifting screening from relying on imaging alone to detecting molecular signals in the blood," Hu said. He added that the team hopes to expand use of the test to community clinics and health screening centers, greatly increasing early detection rates countrywide.