39 P - Chemotherapy induced leukopenia as a predictor of response in small cell lung cancer (SCLC)

The correlation between chemotherapy (CT) induced toxicity and therapeutic efficacy in cancer patients (pts) has been studied only occasionally. Our aim was to evaluate the possible relationship between CT induced leukopenia and response to treatment in 238 SCLC pts treated within two prospective multicenter studies. CT regimens included CEE (cyclophosphamide, etoposide, epirubicin; in 128 pts) or VEC (vincristine, epirubicin, cyclophosphamide; in 110 pts). both given every 3 weeks. The highest score of leukopenia within the first 2 CT cycles was recorded. The response was evaluated after a median of 4 cycles (range 2–5). The objective response rate (CR and PR) for the whole group was 68%. Response was seen in 92% of pts who developed leukopenia and in 43% of pts whose WBC remained normal (p < 0.000). In multifactorial analysis including also other treatment- and patient-related factors, independent correlation with response to CT was found for leukopenia (p < 0.000, coef = 0.2), the CT regimen used (p = 0.002, CEE being more toxic and more effective) and the number of CT cycles. Response was not related to patient sex, age, performance status, pre-study weight loss, extent of disease and dose intensity. No significantly better survival was observed in pts who developed leukopenia during the first 2 cycles (p = 0.09). Additional analysis showed however, that both response rate (p < 0.000) and survival (p = 0.009) was better in pts who developed leukopenia during the first 4 CT cycles. It seems that there is a close relationship between CT induced leukopenia and tumor response. Further studies concerning other tumors or other side effects are warranted.