Nuclear DNA content and survival in medullary thyroid carcinoma. Swedish Medullary Thyroid Cancer Study Group

In a nationwide study of medullary thyroid carcinoma, the relation between nuclear DNA content and survival was studied in 211 patients with complete follow-up of up to 27 years. Morphologically identified tumor cells were analyzed by an image cytometric method. The DNA histograms were classified (1) by an objective method in which the degree of aneuploidy was defined as the percentage number of tumor cells with DNA values exceeding the 90th percentile of diploid control cells (P90), and (2) according to a subjective evaluation of whether the DNA profiles represented a euploid or an aneuploid DNA pattern. Both classifications separated groups with marked differences (P less than 0.001) in survival. A multivariate proportional hazards analysis indicated that each method provided additional information when the other one was taken into account. In patients whose tumors were classified according to the objective P90 method 1, the relative hazards (with 95% confidence interval) in the groups with P90 values of 36% to 69% and greater than or equal to 70% were 1.6 (0.9-2.8) and 2.1 (1.1-4.0) respectively, compared with the reference group. With the subjective method 2 the corresponding figure for the group with aneuploid tumors was 1.7 (1.0-2.0) compared with the group with euploid tumors.