DNA content analysis of human solid tumor is now widely performed by flow cytometric study. One of the most interesting and potentially observation in this field is that proliferative activity(S-Phase fraction of cell cycle) may profoundly affect the prognosis.

S-Phase fraction(SPF) have been measured by flow cytometric method using tumor cells isolated from paraffin embedded tissue. To evaluate the prognostic significance, SPF of small lung cancer cell was assessed in 42 patients who died after receiving anticancer chemotherapy.

1) Mean survival time of patients with small cell lung cancer was 190(± 156) days, Survival time were shortened, when TNM stage and PS scale were advanced. 2) Mean value of SPF of patients with small cell lung cancer was 27.4(±8.5)%. SPF had nothing to do with advance of TNM stage and PS scale. 3) In each identical TNM stage, there were not statistic significance between SPF and survival times. 4) There was a tendency like that higher SPF, better chemotherapeutic

We could not find statistic significance between SPF and survival times, but SPF was a good predictive factor for chemotherapeutic response.