Could cell kinetics be a predictor of prognosis in non-small cell lung cancer?

Cell kinetics, evaluated as ³H-thymidine labeling index ([³H]TdR LI), was assessed in 72 previously untreated non-small-cell lung cancers (NSCLC) from patients operated on during the period 1978 to 1982 at the Istituto Nazionale Tumori of Milan. Pathologic stage and histology, but not tumor size or cell kinetics, were indicative of clinical outcome on the overall series. However, in stage I patients, relapse-free survival and overall survival were significantly higher for patients with low [³H]TdR LI or squamous cell tumors than for patients with high [³H]TdR LI or non-squamous cell tumors. When both cell kinetics and histology were taken into consideration, the probability of 5-year survival was 100% for patients with slowly proliferating squamous cell carcinomas compared to only 29% for patients with rapidly proliferating non-squamous cell carcinomas. The data suggest that cell kinetics and histology could represent an important means to identify a subgroup of patients with high risk of relapse within stage I NSCLC.