Uterine cervical cancer displaying tumor-related leukocytosis: a distinct clinical entity with radioresistant feature

Background: Tumor-related leukocytosis (TRL) is occasionally found in patients with nonhematopoietic malignancies. We investigated the clinical implication of TRL and individualized treatment for TRL-positive cervical cancer, as well as the underlying biological mechanism.

Methods: Clinical data from 258 cervical cancer patients treated with definitive radiotherapy were analyzed to investigate the association between TRL and treatment outcome. Clinical samples, cervical cancer cell lines, and a mouse model of cervical cancer were used to examine the mechanisms responsible for TRL in cervical cancer, focusing on the role of tumor-derived granulocyte colony-stimulating factor (G-CSF) and myeloid-derived suppressor cells (MDSCs). All statistical tests were two-sided.

Results: TRL was statistically significantly associated with younger age (Wilcoxon rank sum test, P = .03), larger tumor size (Wilcoxon rank sum test, P = .006), advanced clinical stage (χ(2) test, P = .01), and shorter overall survival (Cox proportional hazard modeling and Wald tests, P < .001). Among cervical cancer patients, TRL was associated with upregulated tumor G-CSF expression (χ(2) test, P < .001), elevated serum G-CSF levels (Student t test, P = .03), larger spleens (Student t test, P = .045), and increased MDSC frequencies in the blood (Student t test, P < .001) compared with the TRL-negative patients. In vitro and in vivo experiments revealed that tumor-derived G-CSF was involved in the underlying causative mechanism of TRL and MDSCs induced by tumor-derived G-CSF are responsible for the rapidly progressive and radioresistant nature of TRL-positive cervical cancer. The administration of anti-Gr-1 neutralizing antibody or the depletion of MDSCs by splenectomy (n = 6 per group) inhibited tumor growth and enhanced radiosensitivity in TRL-positive cervical cancer xenografts (Wilcoxon rank sum test, P = .008 and P = .02, respectively).

Conclusions: TRL is associated with resistance to radiotherapy among cervical cancer patients, and MDSC-targeting treatments may have therapeutic potential in these patients.