Prognostic Significance of the Proliferation Index in Surgically-Resected Non-Small Cell Lung Cancer

Objective: To determine the utility of measuring the tumor proliferation index as a prognostic marker in patients with non—small-cell lung cancer. Design: Immunostaining for the proliferationassociated antigen Ki-67, quantitated using computerassisted image cytometry, was used to derive the tumor proliferation index for 61 fresh-frozen, banked specimens of non—small-cell lung cancer. DNA ploidy was measured concomitantly for all specimens. A median follow-up of 38 months was achieved for survival analyses. Setting: A large southeastern United States private referral institution and affiliated hospital provided the study environment. Participants: A consecutive, convenience sample of 61 patients was enrolled based on resected tissue preservation and viability over a five-year accruement. Main Outcome Measures: Significant associations between DNA content, proliferation index, established clinicopathological parameters, and outcome were examined. Results: A significant inverse association between patient survival and tumor proliferation index was found that was independent of other established clinicopathological predictors of outcome. Patients whose tumors harbored a proliferation index of less than 3.5 survived significantly longer than patients with tumors demonstrating higher values. No association between DNA content and proliferation index was uncovered. Conclusion: Measurement of the proliferation index, as derived from quantitative Ki-67 immunostaining and analyzed by image cytometry, may provide significant complementary, if not independent, prognostic information for patients with non—small-cell lung cancer