Paraneoplastic leukemoid reaction as a marker of tumor progression in non-small cell lung cancer

AbstractBackgroundParaneoplastic leukemoid reaction (PLR) is a well-described entity in which the white blood cell count expands to greater than 50,000/mm3 in association with malignancy. It is thought to occur in approximately 10–15% of cancers. Notably, PLR is known to be predictive of a poor prognosis. Recent work has demonstrated that there may be a relationship between PLR activated by intratumoral production of granulocyte colony-simulating factor (G-CSF), the RAS/RAF/MEK pathway and tumorogenesis. Specifically, activation of the RAS/RAF/MEK pathway is thought to regulate G-CSF production, which in turn, mediates expansion and mobilization of cells that produce factors that promote tumor metastasis.Methods/resultsIn this report we demonstrate the PLR response to treatment in a patient with non-small cell lung cancer. Additionally, we demonstrate elevated G-CSF in the patient׳s serum 507pg/ml (0–39.1pg/ml) and positive staining by immunohistochemistry of G-CSF in the patient׳s tumor tissue. Finally, we describe a possible pathway by which this promotes tumor spread.ConclusionThough G-CSF has been traditionally viewed as a prognostic marker, here we provide evidence that it may be a valuable marker to investigate for treatment response at a cellular level