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 proliferation-associated antigen Ki-67, quantitated using computer-assisted 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.