Paraneoplastic Leukocytosis and Thrombocytosis as Prognostic Biomarkers in Non-small Cell Lung Cancer

Background and Objectives: Search for inexpensive laboratory markers have identified associations between blood counts and lung cancer outcomes. In this study, we evaluated the prognostic value of paraneoplastic leukocytosis (p-Leukocytosis) and paraneoplastic thrombocytosis (p-Thrombocytosis) in patients with non-small cell lung cancer (NSCLC). We also studied their relation to the expression of commonly detected molecular markers. 
Methods: We conducted a retrospective chart review on 571 consecutive NSCLC patients over a 10 year period. Blood counts were recorded at the time of cancer diagnosis. Kaplan-Meier survival curves were used to compare overall survival (OS) between patients with and without p-Leukocytosis (or) p-Thrombocytosis (p-Leuko/Thrombocytosis). Cox regression was used to determine if leukocytosis/thrombocytosis was a predictor of OS in NSCLC.
Results: Patients with p-Leukocytosis and p-Thrombocytosis had a significantly poorer survival compared patients with normal blood counts (P<0.001). In a multivariate survival analysis, both continued to correlate even when adjusted for histology, gender, stage and chemotherapy (P<0.01, 0.03 respectively). Stage I and II NSCLC with p-Leuko/Thrombocytosis did not perform poorly compared to stage I/II NSCLC patients without paraneoplasia. Patients with the combined leukothrombocytosis syndrome did not have worse outcomes compared to those with either paraneoplastic syndrome alone. 
Conclusions: p-Leuko/Thrombocytosis is an accessible laboratory parameter of prognostic value in NSCLC. Evidence of p-Leuko/Thrombocytosis portends poor survival. The role of various cytokines in tumor pathobiology provides a rationale for identifying cytokine factors responsible for the paraneoplasia and administering anti-cytokine therapies alongside traditional chemotherapy in an attempt to improve survival outcomes in these subset of patients