PLK1 and non-small cell lung carcinoma: Combining PLK1 with TNFAIP6 has a more significant prognostic association than either gene alone in metastatic NSCLC, suggesting that high expression of both TNFAIP6 and PLK1 could be a negative prognostic marker for survival among metastatic NSCLC patients and that PLK1 and TSG6 are valuable therapeutic targets for metastatic NSCLC treatment.