Blood Test May Predict Lung Cancer Risk 5 Years Before Diagnosis: Study

Lung cancer remains the leading cause of cancer-related deaths worldwide, largely because it is often diagnosed at an advanced stage when treatment options are limited. But a groundbreaking international study has raised hopes that the disease could one day be identified years before symptoms appear. Researchers have discovered a unique "blood signature" consisting of 14 proteins that may predict an individual's risk of developing lung cancer more than five years before diagnosis. The findings, published in the journal Cell, suggest that subtle biological changes linked to inflammation and cancer development can be detected long before a tumour becomes visible on scans or causes symptoms.

Scientists say the discovery could transform how lung cancer is prevented and detected, allowing doctors to identify high-risk individuals earlier and potentially intervene before cancer develops. The study also provides new insights into the role of chronic inflammation in lung cancer, opening avenues for targeted prevention strategies.

While experts caution that the test is not yet ready for clinical use, the findings represent a major step toward more personalised cancer screening and prevention.

Why Early Detection Matters

According to the World Health Organization (WHO), lung cancer is one of the most commonly diagnosed cancers globally and remains the leading cause of cancer death. Survival rates are heavily influenced by when the disease is detected.

Research shows that early-stage lung cancer can often be treated successfully, while advanced-stage disease carries significantly poorer outcomes. A large international analysis published in Nature Communications notes that five-year survival can exceed 60% for early-stage disease but may fall to around 6% once cancer has spread extensively. (Nature)

Despite advances in imaging, many cases are still diagnosed only after symptoms such as persistent cough, chest pain, breathlessness or unexplained weight loss appear.

What Did The New Study Find?

The research was led by scientists from the Walter and Eliza Hall Institute of Medical Research (WEHI) in Australia and involved the analysis of approximately 48,000 blood samples from multiple international cohorts. Researchers identified a pattern of 14 circulating proteins that consistently signalled increased lung cancer risk years before diagnosis.

Importantly, the protein signature did not appear to reflect the presence of an existing tumour. Instead, it seemed to capture biological processes occurring much earlier in the disease pathway.

According to the researchers, the protein pattern was associated with chronic inflammation in lung tissue, a known driver of cancer development. The signature remained predictive even more than five years before diagnosis, suggesting that the earliest stages of cancer formation may begin long before clinical detection becomes possible.

The Link Between Inflammation And Cancer

Scientists have long suspected that chronic inflammation contributes to cancer development. Inflammation is the body's natural response to injury, infection or harmful exposures. However, when inflammation becomes persistent, it can damage tissues, promote abnormal cell growth and create an environment favourable for cancer.

The newly identified protein signature appears to be linked to inflammatory pathways involving interleukin-1 beta (IL-1b), an immune signalling molecule previously implicated in cancer development. Researchers found evidence that these inflammatory changes may precede the appearance of detectable tumours by several years.

The findings support growing evidence that lung cancer is not simply a disease of genetic mutations but also one influenced by long-term interactions between the immune system and environmental exposures.

Could This Lead To Better Screening?

Current lung cancer screening programmes primarily focus on people with a significant smoking history, typically using low-dose CT scans. However, a substantial number of lung cancers occur in people who do not meet current screening criteria, including former smokers and never-smokers.

Researchers believe a blood-based risk test could help identify individuals who would benefit most from further screening, making programmes more precise and potentially detecting cancers earlier. Previous international studies have already demonstrated the potential of blood-based biomarkers for identifying individuals at elevated risk of lung cancer years before diagnosis. In one large Nature Communications study, scientists identified 36 circulating proteins associated with imminent lung cancer diagnosis up to three years before detection. The new 14-protein signature appears to extend that predictive window even further.

Could Prevention Be Possible?

Perhaps the most intriguing aspect of the study is its potential role in prevention. Researchers examined previous clinical trial data involving canakinumab, an anti-inflammatory drug that blocks IL-1b. They found that individuals with high levels of the protein signature appeared to experience a substantially lower risk of developing lung cancer when treated with the drug.

While this observation does not prove that anti-inflammatory treatment can prevent lung cancer, it raises the possibility that future prevention strategies could be tailored to people identified as high-risk through blood testing.

Experts stress that further clinical trials will be needed before any preventive treatment can be recommended.

What Are The Limitations?

Despite the excitement, researchers emphasise that the test remains experimental.

Several important questions remain unanswered:

• The blood test is not yet commercially available.
• Researchers must validate the findings in broader populations.
• False-positive and false-negative rates require further evaluation.
• It is unclear how best to integrate the test into existing screening programmes.
• More studies are needed to determine whether early intervention based on the blood signature improves long-term outcomes.

Scientists also note that a predictive biomarker is not the same as a diagnostic test. A positive result would indicate elevated risk rather than confirm the presence of cancer.

What Does This Mean For India?

Lung cancer is among the leading causes of cancer deaths in India, with tobacco use, air pollution, occupational exposures and indoor biomass smoke contributing significantly to risk.

A simple blood test capable of identifying high-risk individuals years before diagnosis could be particularly valuable in resource-constrained settings where access to advanced imaging is limited. If validated, such tools may eventually help expand risk-based screening beyond traditional smoking criteria and improve early detection rates.

The discovery of a 14-protein blood signature capable of predicting lung cancer risk more than five years before diagnosis marks a significant advance in cancer research. Rather than detecting an existing tumour, the test appears to identify early biological changes linked to inflammation and cancer development.

Although the technology is still in the research phase, experts believe it could eventually transform lung cancer screening, risk assessment and even prevention. For a disease that remains the world's deadliest cancer, the ability to identify risk years before diagnosis could represent a major step toward saving lives.

Disclaimer: This content including advice provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.