Does chemotherapy-induced leukopenia predict a response in small cell lung cancer?

The correlation between chemotherapy-induced toxicity and treatment outcome in cancer patients has not been studied thoroughly. Our aim was to evaluate whether there is any relationship between chemotherapy-induced leukopenia and response to treatment in small-cell lung cancer (SCLC). Data derived from records of 228 patients treated within two prospective multicentre phase II studies were analysed. In the first study (101 patients) chemotherapy included vincristine, epirubicin and cyclophosphamide and, in the second (127 patients), cyclophosphamide, etoposide and epirubicin; both regimens were given every 3 weeks. In the present analysis, the correlation between treatment outcome (response rate and survival) and highest scores of leukopenia within the first two and up to the fourth chemotherapy cycle, respectively, was evaluated. The objective response rate for the entire group was 66%; 53% in patients whose white blood cells remained normal and 85% in those who developed leukopenia within the first two cycles (P = 0.000). In multifactorial analysis, also including other treatment- and patient-related factors, independent correlation with response to chemotherapy was found for leukopenia (P = 0.001), chemotherapy regimen (P = 0.002) and the combined relative dose intensity (P = 0.018), but not for patient sex, age, performance status, pre-study weight loss, extent of disease and initial white blood cell count. Leukopenia within the first two cycles of chemotherapy was not correlated with survival, whereas such correlation for leukopenia occurring up to the fourth cycle was at the borderline level (P = 0.06). These findings suggest a relationship between chemotherapy-induced leukopenia and tumour response in SCLC.