Platelet counts were evaluated in 714 patients with advanced
non-small cell lung cancer (N-SCLC),
small cell carcinoma of the lung (SCCL), and
colon cancer entered to a clinical trial. Patients had not received prior
chemotherapy. Platelet counts were not different in patients who had received
radiation therapy prior to entry to the study. In comparison to the other
tumor types, patients with N-SCLC demonstrated an increased prevalence of
thrombocytosis (counts greater than 400,000/mm3), higher platelet counts at the time of entry to the study, higher over all mean platelet counts, relative preservation of high platelet levels during
disease progression, and no relationship between platelet numbers and the amount of
chemotherapy given. By contrast, platelet counts in patients with SCCL were negatively correlated with the absolute amount of
cyclophosphamide and
adriamycin given, and declined most dramatically with
disease progression and death. Platelet numbers did not correlate with
fibrinopeptide A or
fibrin split product levels suggesting that
disseminated intravascular coagulation or fibrinolysis may have had less influence on platelet numbers than certain other factors. By contrast, significant correlations were found for all three
tumor types between platelet numbers and other indicators of bone marrow function including
anemia, total leukocyte count, and absolute neutrophil count; and the
fibrinogen level. Based upon these findings, we postulate that the host response to
malignancy, possibly in the form of production of bone marrow-stimulating
cytokines, may play a prominent role in regulation of platelet counts in these (and perhaps other)
neoplasms, and that a particularly prominent and persistent degree of marrow stimulation exists in patients with N-SCLC.