Monitoring tumor cell kinetics in patients receiving chemotherapy for small cell lung cancer.

To monitor in vivo tumor cell changes in patients receiving chemotherapy for small cell lung cancer, tumor cell kinetics, cytomorphometry and cytomorphology during the first course of combination chemotherapy were studied in three patients with histologically verified small cell lung cancer. The tumor cells were aspirated from metastatic lesions both prior to treatment and twice weekly after the administration of chemotherapeutic agents. Morphologic observation of tumor cells was done with a light microscope after Riu's staining. The nuclear area was measured with a Mini-magiscan. The nuclear DNA content of aspirated tumor cells was measured with a scanning microdensitometer after the modified Feulgen reaction. The cell population in the cell cycle was estimated with a cumulated percentage scale from the DNA histogram. Marked cytolysis with enlarged nuclei of the remaining cells and cell cycle perturbation occurred within one week after initiation of chemotherapy. There was a decrease in the G1 cell population (from 53.7 +/- 10.0% to 12.7 +/- 3.5%) and an increase in cells in the G2 phase (from 27.0 +/- 8.7% to 68.3 +/- 5.6%), which corresponded to the cells with enlarged nuclei (50.4% to 68.7% increase) after chemotherapy. The proportion of cells in S phase was slightly increased (from 19.3 +/- 4.1% to 20.0 +/- 3.7%). The degree of cell cycle perturbation correlated well with the cytomorphologic changes during chemotherapy.