DNA ploidy patterns of tumors diagnosed as metachronous or recurrent lung cancers

The relationship between the first tumor and the second tumor resected in 8 patients with non-small cell lung cancer was analyzed using deoxyribonucleic acid (DNA) flow cytometry. Of the 8 patients, 6 were clinically diagnosed as having metachronous lung cancers and 2, local recurrent tumors. The mean interval between operations in patients with metachronous lung cancers was 62 months (range, 15 to 128 months). Both tumors showed the same histology in 4 patients and a different histology in 2. In the 2 patients with local recurrent tumors, the interval between operations was 9 months and 39 months. In the analysis of DNA flow cytometry of the first and second tumors in the same patient, the tumors were defined as independent of each other when one tumor showed diploidy and the other, aneuploidy, or when each DNA index of abnormal clones between two aneuploid tumors was different. When both tumors showed diploidy or when at least one DNA index of abnormal clones between two aneuploid tumors was identical, the tumors were defined to be related to each other. According to these criteria, in 5 (83%) of the 6 patients clinically diagnosed as having metachronous lung cancers, the second tumor was classified as independent of the first tumor. On the other hand, in the 2 patients clinically diagnosed as having recurrent tumors, the second tumor was judged to be related to the first tumor. These data suggest that DNA flow cytometric analysis of tumors may be of value in the diagnosis of metachronous lung cancers.