Flow microfluorometric deoxyribonucleic acid (DNA) analysis supplementing routine histopathologic diagnosis of biopsy specimens.

Flow microfluorometric DNA analysis was applied on a routine basis additionally to the conventional pathologic diagnostics of biopsy samples. The evaluation of the DNA distributions for the determination of the fractions of cells in different stages of the cell cycle was complicated by varying portions of background debris, which was generally found to be present in suspensions of single dispersed cells prepared from solid tissues. By means of computerized subtraction of exponentially decreasing corrections, it was possible to clear the original flow microfluorometric distributions. The contribution of background debris was found to cause erroneous overestimation, particularly in the evaluation of low S-phase fractions. By means of the corrections, even samples containing more than 65 per cent nuclear fragments could be evaluated with sufficient accuracy. The correct evaluation of the S-phase fraction possibly could indicate the degree of differentiation and proliferative activity of tissues. Low S-phase fractions within the range of normal regeneration were found in benign alterations and well differentiated carcinomas. In contrast, S-phase fractions up to 40 per cent were present in poorly differentiated tumors with extended cellular atypia, largely varying nuclear size and staining properties. The combination of conventional pathologic diagnostics with quantitative determination of the fractions of cells within the stages of the cell cycle in biopsy samples on a routine basis could supplement the diagnoses by therapeutically relevant information.