Prognostic value of flow-cytometric DNA analysis in breast cancer

The most important factor influencing prognosis in breast cancer is its biological aggressiveness, generally expressed by parameters such as tumor size, number of metastatized lymph nodes, histological grade and receptors status. In recent years, the proliferative rate of tumors has been widely investigated in an attempt to define additional prognostic factors. New factors have thus been proposed to evaluate the DNA content and cellular cycle of neoplastic cells (1-5). Tumor cell nuclear DNA content has been recognized as "one of the best prognostic indexes" in a wide range of human cancers. Barlogie suggested that the presence of an abnormal DNA stemline (DNA aneuploidy) should be regarded as "the single most reliable marker of neoplasia". Also the clinical value of flow-cytometric DNA ploidy analysis has recently been examined on paraffineembedded archival tumor samples and established in carcinomas of some organs including breast, lung and prostate (2-4). Many studies have showed correlations between cellular DNA content, measured by flow-cytometry and other pretreatment factors (1,2,5). In addition, the relationship between the results of flow-cytometric DNA analysis, with particular attention to S-phase fraction, and clinical course, has been examined. Patients whose tumors have a low proportion of cells in S-phase do appear to have a better prognosis. Recent reports also show a relapse free survival and survival advantage for patients with diploid tumors. In general, available data suggest that aneuploidy is an indicator of greater tumor aggressiBackground. Prognosis of breast cancer is mostly dependent on the biological aggressiveness of the neoplasia. New parameters, including DNA content and cellular cycle of neoplastic cells, are now routinely used to assess malignancy. In this work we have studied the clinical value of flow-cytometric DNA ploidy analysis. Particular attention has been addressed towards establishing if these values give additional information to that of histological examination. Methods. Patients who underwent surgical treatment for primary breast cancer have been selected. At present, all of them are still living, no one has long-distance metastases and all are free of tumor relapses. Thin sections were tested, after staining, by a Coulter Epics Profile flow cytometer. DNA-index (DI) was assumed to be 1.0 if only a single G0/1 peak was evident. When a second peak was clearly identified (more than 10%), this was considered as an indicator of clonal abnormality of the DNA content. The slides were also examined to define the stage of the neoplasia. Grading was made by evaluation of tubular growth, nuclear polymorphy and number of mitosis. Cell cycles, DI and coefficent of variation G0-G1 peak were compared. Results. A significant relationship among histological stage, S-phase fraction (SPF) and ploidy was observed. In accord to the survival rate, nodule size and SPF determine 3 classes of infiltrating ductal carcinoma with negative axillary lymph nodes. Our twenty cases show a correlation between DNA ploidy and histological stage. In fact there are no aneuploid tumors in stage I group, all cases of stage III and most of stage II are aneuploid. We did not find a correlation with survival. Conclusions. The new screening methods and the improvement of the available methodologies have permitted an earlier diagnosis of breast cancer. Unfortunately, according to our data, flow-cytometric information does not seem to offer predictive elements about tumor clinical outcome.