Scientists have identified warning signals in the blood that can predict lung cancer more than five years before the disease is diagnosed, offering a potential breakthrough in the fight against one of India's deadliest cancers, where most cases are detected at an advanced stage, reported TOI. The findings come at a time when lung cancer cases in India are projected to increase from around 63,700 in 2015 to more than 81,000 by 2025. Nearly 80-85% of patients are diagnosed only after the disease has progressed significantly, limiting treatment options and survival outcomes. Published in the journal Cell, the study identified a 14-protein blood signature capable of predicting lung cancer risk a median of 5.6 years before diagnosis. Researchers say the discovery could help identify high-risk individuals earlier, allowing for closer monitoring, screening and preventive interventions, reported TOI. Dr Abhishek Shankar, radiation oncologist at AIIMS Delhi, told TOI that the test should be viewed as a risk-assessment tool rather than a screening test. "The blood-based protein signature does not detect a tumour but identifies people who may be at higher risk of developing lung cancer in the future. Such individuals can then undergo more definitive screening, such as low-dose CT scans. The finding is an important scientific advance because it opens the possibility of identifying high-risk individuals years before cancer develops and may eventually help guide preventive interventions. However, these protein signatures will need validation in Indian populations before they can be widely applied here," he said. For the study, researchers analysed blood samples and health records from more than 48,000 participants in the UK Biobank. They found that a combination of 14 proteins, along with factors such as age, smoking history and chronic lung disease, predicted future lung cancer risk more accurately than existing assessment models. The results were further validated across eight international cohorts involving more than 2,000 lung cancer cases, strengthening confidence in the findings. Researchers also observed that the protein signature was elevated not only among smokers but also among individuals exposed to particulate air pollution. The finding carries particular significance for India, where worsening air quality has emerged as a major public health challenge. The study additionally provides new insights into how lung cancer develops. According to researchers, air pollution, cancer-causing genetic mutations and inflammation driven by the immune molecule IL-1 may interact through common biological pathways that promote tumour formation.