Surreal digital illustration of a brain intertwined with lung tissue, illuminated by a blood sample test tube.

Can a Simple Blood Test Predict Brain Metastasis in Lung Cancer?

Lena Kashyap in Health & Wellness December 2025 • 5 min read.

"New research explores how a routine blood test, the Systemic Immune-Inflammation Index (SII), could help predict outcomes for lung adenocarcinoma patients with brain metastases, offering new insights for personalized treatment strategies."

Brain metastases (BM), where cancer spreads to the brain, are a significant concern for individuals with lung adenocarcinoma. Occurring in approximately 40% of these patients, BM often leads to a challenging prognosis, with survival typically ranging from just 4 to 6 months post-diagnosis. While treatments like whole-brain radiotherapy (WBRT) and stereotactic radiosurgery (SRS) can extend survival, predicting how each patient will respond remains a complex puzzle.

In recent years, targeted therapies like epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) have shown promise, particularly for those with specific EGFR mutations. These treatments can extend median survival times to between 12.9 and 18.8 months. However, clinicians need better tools to determine the most appropriate treatment for each patient, guiding both current decisions and future research directions.

A promising avenue of investigation involves the systemic immune-inflammation index (SII), a measure derived from routine blood tests that reflects the balance of immune cells in the body. Emerging research suggests that SII could serve as a valuable prognostic marker. A recent study aimed to evaluate whether SII could predict outcomes in lung adenocarcinoma patients with brain metastases, considering the presence of EGFR mutations. This article delves into the findings of that study, exploring the potential of SII to refine treatment strategies and improve patient outcomes.

Decoding SII: How This Blood Test Could Change Lung Cancer Treatment

Surreal digital illustration of a brain intertwined with lung tissue, illuminated by a blood sample test tube.

The study, published in Genes & Immunity, retrospectively examined 310 patients diagnosed with brain metastases from lung adenocarcinoma. All patients had their EGFR mutation status determined. The researchers calculated the SII using a simple formula: platelet count multiplied by neutrophil count, divided by lymphocyte count. This number reflects the interplay between different components of the immune system. Higher SII values generally indicate a more pronounced inflammatory response within the body.

The study established a cut-off value for SII at 1218.81. Patients with SII values below this threshold experienced longer survival times. Statistical analyses confirmed that SII, along with other factors like age, smoking history, and EGFR mutation status, significantly impacted overall survival. Notably, SII appeared to have a more pronounced effect in patients without EGFR mutations. This suggests that SII's prognostic value might vary depending on the specific genetic characteristics of the tumor.

Simple and Accessible: SII is derived from routine blood tests, making it readily available and cost-effective.
Reflects Immune Status: SII integrates lymphocyte, neutrophil, and platelet counts to provide a comprehensive snapshot of the body's immune response.
Potential for Personalized Treatment: SII may help identify patients who would benefit most from specific therapies, such as EGFR-TKIs or immunotherapies.

While the study provides valuable insights, it is essential to acknowledge its limitations. The retrospective design means that researchers looked back at existing data, which can introduce biases. Additionally, the study was conducted at a single center, and the patient population may not fully represent the broader population of lung adenocarcinoma patients with brain metastases. Further research is needed to validate these findings in larger, multi-center studies.

The Future of SII in Lung Cancer Management

The study highlights the potential of the systemic immune-inflammation index (SII) as a valuable tool for predicting outcomes in lung adenocarcinoma patients with brain metastases. SII offers a simple, accessible, and cost-effective way to assess a patient's immune status and potentially personalize treatment strategies. While further research is needed to validate these findings and establish standardized cut-off values, SII holds promise for improving the management of this challenging disease. As researchers delve deeper into the interplay between inflammation, genetics, and treatment response, SII could become an integral part of the clinician's toolkit, ultimately leading to better outcomes for patients facing brain metastases from lung adenocarcinoma.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1038/s41435-018-0050-z, Alternate LINK

Title: Prognostic Role Of The Systemic Immune-Inflammation Index In Brain Metastases From Lung Adenocarcinoma With Different Egfr Mutations

Subject: Genetics (clinical)

Journal: Genes & Immunity

Publisher: Springer Science and Business Media LLC

Authors: Hongwei Li, Guochao Wang, Huanhu Zhang, Xin Song, Jianzhong Cao, Xiaqin Zhang, Ruiqi Xue, Weili Wang, Sufang Jia, Zhengran Li

Published: 2018-11-09

Everything You Need To Know

What exactly is the Systemic Immune-Inflammation Index (SII)?

The Systemic Immune-Inflammation Index (SII) is a value calculated from a routine blood test. It uses a formula involving platelet, neutrophil, and lymphocyte counts to reflect the balance of immune cells in the body. A higher SII typically indicates a more pronounced inflammatory response. This is significant because the level of inflammation can be related to the progression of cancer.

Why is the Systemic Immune-Inflammation Index (SII) considered important in treating lung adenocarcinoma with brain metastases?

The Systemic Immune-Inflammation Index (SII) is significant because it can potentially predict how lung adenocarcinoma patients with brain metastases will respond to treatment. Research suggests it could help doctors determine who would benefit most from therapies like EGFR-TKIs or immunotherapies. This helps to personalize treatment strategies for each patient. Furthermore, it is cost effective.

What are epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs), and how are they relevant?

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are targeted therapies used particularly for lung adenocarcinoma patients with specific EGFR mutations. These inhibitors work by blocking the activity of the EGFR protein, which is often overactive in cancer cells, thus slowing or stopping cancer growth. They are important because they can extend median survival times in patients with these specific mutations. The Systemic Immune-Inflammation Index (SII) may help predict which patients will benefit most from EGFR-TKIs.

What are brain metastases, and why are they a concern in lung adenocarcinoma?

Brain metastases (BM) occur when cancer cells spread from the primary tumor (in this case, lung adenocarcinoma) to the brain. This is a significant concern because it often leads to a challenging prognosis, with survival typically ranging from just 4 to 6 months post-diagnosis. Brain metastases were present in all patients referenced. The presence of brain metastases highlights the need for better predictive tools, such as the Systemic Immune-Inflammation Index (SII), to improve treatment strategies and patient outcomes.

What are whole-brain radiotherapy (WBRT) and stereotactic radiosurgery (SRS), and how do they fit into the context?

Whole-brain radiotherapy (WBRT) and stereotactic radiosurgery (SRS) are treatment options often used to manage brain metastases. WBRT involves delivering radiation to the entire brain to kill cancer cells, while SRS is a more targeted approach that delivers high doses of radiation to specific tumors in the brain. These treatments can extend survival, but predicting how each patient will respond remains a challenge. The Systemic Immune-Inflammation Index (SII) may help in predicting the likely effectiveness of these treatments, thus aiding in treatment decisions.