# Monocyte-Driven Systemic Biomarkers and Survival After Pulmonary Metastasectomy in Metachronous Lung-Limited Oligometastatic Disease: A Retrospective Single-Center Study

## TL;DR

This study identifies monocyte-based biomarkers that predict survival after surgery for lung-limited cancer spread, offering new tools for patient selection.

## Contribution

Monocyte-driven biomarkers like MAR and SIRI are shown to independently predict survival outcomes in pulmonary metastasectomy candidates.

## Key findings

- MAR had the highest discriminative ability for mortality with an AUC of 0.749.
- MAR and SIRI independently predicted overall and progression-free survival in multivariable analyses.
- Monocyte-weighted indices added prognostic value beyond traditional anatomic criteria.

## Abstract

Background/Objectives: Metachronous lung-limited oligometastatic disease represents a biologically heterogeneous state in which patient selection for pulmonary metastasectomy remains challenging. While systemic inflammation–nutrition indices have shown prognostic value across malignancies, their relevance in this strictly defined surgical setting is not well established. Methods: We conducted a retrospective single-center cohort study including 109 patients with isolated metachronous pulmonary recurrence who underwent curative intent R0 metastasectomy between September 2015 and April 2024. Preoperative systemic biomarkers, including neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII), systemic inflammation response index (SIRI), pan-immune-inflammation value (PIV), and monocyte-to-albumin ratio (MAR), were evaluated using receiver operating characteristic (ROC) analysis and multivariable Cox models to determine their association with overall survival (OS) and progression-free survival (PFS). Clinicopathological variables, such as lymph node involvement and metastatic burden, were incorporated into the adjusted models. Results: The median age of the cohort was 61 years (range, 29–82 years), and the sex distribution was balanced (48.6% female and 51.4% male), with 62.4% of patients being younger than 65 years. Among the systemic indices evaluated, monocyte-weighted biomarkers demonstrated the strongest prognostic performance. The MAR showed the highest discriminative ability for mortality (AUC, 0.749; p < 0.001), followed by the SIRI (AUC, 0.682; p = 0.007). In multivariable analyses, MAR independently predicted OS (p = 0.043) and PFS (p = 0.023), while SIRI independently predicted PFS (p = 0.043). Lymph node involvement remained the dominant adverse prognostic factor for both outcomes (p < 0.001); however, monocyte-weighted indices provided additional prognostic value beyond conventional anatomic criteria. Conclusions: Preoperative SIRI and MAR capture host immune–metabolic states that are relevant to postoperative trajectories and may refine risk stratification in candidates for pulmonary metastasectomy. These readily obtainable markers warrant prospective validation within biologically integrated selection frameworks.