The critical role of serum thymidine kinase 1(STK1) in predicting prognosis for immunotherapy in T4 stage lung squamous cell carcinoma.

Purpose: The role of serum thymidine kinase 1 (STK1) in predicting the prognosis of T4-stage lung squamous cell carcinoma (LUSC) with immunotherapy is the focus of our work.

Methods: A total of 180 LUSC patients were enrolled. In this study, according to the T stage, the patients were divided into two groups: the T1-T2 stage and the T3-T4 stage. Receiver operating characteristic (ROC) curves were used to determine the best cutoff value for predicting overall survival (OS) outcomes. The next step is to use this cutoff value to introduce univariate and multivariate Cox regression models to screen the prognostic factors in different T stages of LUSC. The association of STK1 with other clinicopathological factors was also determined. Finally, to further explore the link between STK1 and the staging of LUSC patients, we have further divided the staging into T1-3 and T4 stages. We identified factors influencing the prognosis of patients who received immunotherapy in T4 stage LUSC.

Results: First, we determined that the optimal cutoff for STK1 for predicting OS outcome was 1.165 pmol/L. Correlation analysis revealed that STK1 was over-expressed in LUSC patients at the T3-4 stage. Univariate and multivariate analysis showed that immunotherapy was an independent prognostic factor in patients with T4 stage LUSC. In the group of patients who received immunotherapy or not, the STK1 expression level was found to be an independent prognostic factor in T4 LUSC patients receiving PD-1/PD-L1 inhibitor treatment; patients with high levels of STK1 had an increased risk of death (95%CI = 1.028-2.04).

Conclusion: STK1 is associated with a higher T stage and may be an effective prognostic marker for advanced LUSC immunotherapy patients.