TUMOR DOUBLING TIME AND PROGNOSTIC ASSESSMENT OF PATIENTS WITH PRIMARY LUNG-CANCER

Background. Relationships between tumor doubling time (DT) and other p rognostic factors and the risk of death related to these factors are n dt yet fully understood. Methods. Tumor doubling time of primary lung carcinomas of 174 patients, detected in a limited number of local muni cipalities during a limited period, was calculated using the Schwartz formula. Survival rate of the 174 patients was compared with reference to categories of prognostic factors (univariate analyses) and signifi cant factors affecting survival were identified by multivariate analys es using the Cox proportional hazard model. Results. Tumor doubling ti me had a log normal distribution. There was a significant difference i n mean DT in relation to sex, smoking history, presence of symptoms, c ell type, primary tumor factor, and stage. Univariate analyses showed a significant difference in survival in relation to DT, age, sex, meth od of tumor detection, smoking history, symptoms, therapy, cell type, primary tumor (T) factor, regional lymph node (N) factor, distant meta stasis (M) factor, and stage. Multivariate analyses using the Cox's pr oportional hazard model in a stepwise fashion identified a final set o f five significant variables: N factor (P = 0.0001); therapy (P = 0.00 16); M factor (P = 0.0017); T factor (P = 0.0018), and DT (P = 0.0152) . Conclusions. Tumor doubling time was an independent and significant prognostic factor for lung cancer patients.