Can a high neutrophil-to-lymphocyte ratio predict if lung cancer will spread to the brain?
The neutrophil-to-lymphocyte ratio (NLR) is a simple blood test that measures inflammation. A high NLR may signal that lung cancer is more aggressive and more likely to spread. A 2025 meta-analysis found that elevated NLR independently predicts brain metastasis in lung cancer patients. This means doctors can use NLR to identify high-risk patients who may need closer monitoring or preventive treatments.
What the research says
A 2025 meta-analysis of 14 retrospective cohort studies involving 3,643 lung cancer patients found that a high NLR is an independent risk factor for brain metastasis 4. The pooled odds ratio was 1.61 (95% CI: 1.27–2.05), meaning patients with elevated NLR had about 60% higher odds of developing brain metastases 4. This association held even after adjusting for other factors 4.
Other studies support NLR's role in lung cancer. A 2018 study using DNA methylation data found that a higher NLR was linked to a 21% increased risk of lung cancer overall and a 30% increased risk of non-small cell lung cancer 9. In advanced EGFR-mutant non-small cell lung cancer, NLR helped predict how well patients responded to anti-PD-1 inhibitors 10. Another study showed that a low derived NLR after durvalumab treatment was tied to better survival 11.
NLR is part of a broader set of immune-inflammatory markers. The same meta-analysis also looked at platelet-to-lymphocyte ratio (PLR) and lymphocyte-to-monocyte ratio (LMR), but NLR was the strongest predictor for brain metastasis 4. The review on lung cancer brain metastases notes that peripheral immune dysregulation plays a key role in how tumors spread to the brain 3.
What to ask your doctor
- Should I have my neutrophil-to-lymphocyte ratio (NLR) checked regularly to assess my risk of brain metastasis?
- If my NLR is high, what additional monitoring or imaging (like brain MRI) might be recommended?
- Are there treatments or lifestyle changes that can lower NLR and potentially reduce metastasis risk?
- How does NLR compare with other markers like PLR or LMR in my specific type of lung cancer?
- Can NLR be used to guide decisions about preventive brain radiation or other therapies?
This question is drawn from common patient questions about Oncology and answered using cited medical research. We do not provide individualized advice.