Ploidy as a prognostic determinant in surgically treated lung cancer.

The usefulness of tumour ploidy as a prognostic determinant in lung cancer was evaluated in a group of 100 surgically treated patients. Archival paraffin sections of the tumours were analysed by flow cytometry. 45% of tumours were aneuploid and 55% were diploid. Overall, patients with aneuploid tumours had significantly shorter survival (p less than 0.0005) than those with diploid tumours. The subset of patients without nodal involvement at operation and with diploid tumours had a particularly long survival rate. Of these 45 patients 41 (91%) were alive at 2 years compared with only 16 (55%) of the 29 with aneuploid tumours (p less than 0.05). A group with such a favourable prognosis has not previously been recognised except when staging is based on total mediastinal nodal clearance. Ploidy was found to be independent of age, sex, type of operation, site of primary tumour, histology, or TNM category. On Cox multivariate analysis ploidy was the most important and independent prognostic determinant. Therefore, in patients with operable lung cancer, ploidy should be taken into account in planning of management, in estimation of prognosis, and in stratification for treatment trials.