Quantitative pathologic analysis of first and second primary cancers in double tumors of the lung

: In spite of the frequent occurrence of double tumors of the lung, pathologic reports on these tumors are rare. In this study, 34 patients with double tumors (10 metachronous and 24 synchronous) were quantitatively analyzed; in all cases, both the first and second tumors had been completely resected and had adequate archival material. One aim of the study was to investigate whether there was a difference in the malignancy of the first and second tumors, as evaluated from their pathologic features. A second question was whether the length of the disease-free interval between the first and second tumors or the survival could be predicted on the basis of any of the investigated features. It was found that the first and second tumors, whether synchronous or metachronous, were strikingly similar: there was no difference in any of the quantitative pathologic features studied (epithelial percentage, DNA index, mean nuclear area and standard deviation of the nuclear area). It was not possible to predict by either univariate or multivariate analysis from any of the parameters either the length of the disease-free interval between the first and second tumors or the survival. These quantitative pathologic similarities suggest that the malignancy of the second tumor (synchronous as well as metachronous) is not higher than that of the first tumor. Thus, in the case of metachronous tumors, the fact that most of the second tumors (60%) are detected at a higher (inoperable) stage is probably caused by inadequate follow-up and not by increased malignancy.(ABSTRACT TRUNCATED AT 250 WORDS)