Timing of chemotherapy-induced neutropenia is a prognostic factor in patients with metastatic non-small-cell lung cancer: a retrospective analysis in gemcitabine-plus-platinum-treated patients.

Purpose: Chemotherapy-induced neutropenia (CIN) has been associated with better therapeutic results in studies of various tumors. Herein, we explored the relationship between timing (onset) of CIN and clinical outcomes of patients with metastatic non-small-cell lung cancer (NSCLC).

Methods: Patients with stage IV NSCLC receiving at least two cycles of first-line doublet chemotherapy (gemcitabine plus platinum) were reviewed retrospectively. Subjects were stratified by onset of CIN into two groups: early-onset (lowest neutrophil count of cycles 1-2 <2.0 × 10(9)/L) and non-early-onset. The non-early-onset group was further subdivided into late-onset (lowest neutrophil count of cycles 3-6 <2.0 × 10(9)/L) and absence of neutropenia.

Results: A total of 123 patients were studied. Significantly better disease control rate, progression-free survival (PFS), and overall survival (OS) were observed in early-onset versus non-early-onset patients. Median PFS of 5.1 and 3.8 months (p = 0.0016) and median OS of 16.7 and 11.2 months (p = 0.0004) were achieved for these groups, respectively. Patient subsets with late-onset and absence of neutropenia showed similarly poor clinical outcomes, with 4.8 and 3.8 months median PFS (p = 0.5067) and 13.0 and 11.2 months median OS (p = 0.6304), respectively.

Conclusions: Timing of CIN is predictive of prognosis in patients with metastatic NSCLC receiving gemcitabine/platinum doublet chemotherapy. Better clinical outcomes were achieved when onset of neutropenia was early versus late or absent altogether. Further research is warranted to determine whether above findings are applicable to other chemotherapeutic regimens.