Histologic sections of formalin-fixed, paraffin-embedded tissue consisting of 53 surgical specimens, 48 biopsy specimens and 29 intrapulmonary lymph nodes of human non-small cell lung carcinoma were Feulgen stained. The biopsy specimens were obtained before and the surgical specimens after induction chemotherapy (down staging). The integrated optical density (IOD) of tumor cell nuclei was measured using an automated image analysis system, and the attributed minimum spanning trees (MSTs) were computed. The measured features included IOD (DNA content of the nuclei), IOD entropy, S-phase-related fraction (SRF), percentage of tumor cells with an IOD > 5C (P5C), standard deviation of IOD and structural parameters (minimum distance between neighboring tumor cell nuclei, minimum distance between tumor cell nuclei and neighboring lymphocytes, MST entropy, minimum distance between neighboring proliferating tumor cell nuclei, etc.). The measured IOD and MST features showed significant differences in the biopsy specimens as compared to those measured in the surgically excised carcinomas and those growing in the intrapulmonary lymph nodes (lymph node metastases). After down staging, the SRF was significantly diminished, and the percentage of cells with an IOD > 5C increased (P < .05). The survival of patients was remarkably improved if both the carcinomas before and after induction chemotherapy displayed a low SRF, a low number of stemlines and low MST entropy.