Changes in lymphocyte number during cancer chemotherapy and their relation to clinical response

Since hematologic examination during cancer chemotherapy is generally limited to the evaluation of neutrophil and platelet numbers, at present there are no clear data about the possible prognostic significance of changes in lymphocyte number in relation to the clinical efficacy of chemotherapy itself. To obtain some preliminary data about this issue, we have evaluated changes in lymphocyte number and percentage in a group of 50 advanced non-small cell lung cancer patients treated with three cycles of cisplatin (20 mg/m2/day) plus etoposide (100 mg/m2/day) i.v. for three days every 21 days. The clinical response consisted of partial response (PR) in nine (18%), stable disease (SD) in 18 (36%) and progressive disease (PD) in the remaining 23 (46%) patients. The lymphocyte percentage increased during chemotherapy, without, however, a significant difference with respect to the pretreatment values. In contrast, the mean number of lymphocytes observed after the first chemotherapeutic cycle significantly decreased in patients with PD, whereas it increased in patients with PR or SD, even though the difference did not reach statistical significance. These preliminary data, which have to be confirmed in a large number of patients and in patients treated with other chemotherapeutic schedules for different tumor types, seem to suggest that a chemotherapy-induced decline in lymphocyte number may be associated with a lack of efficacy of chemotherapy itself.