Nuclear DNA in intestinal carcinoid tumors. A study before and after cytotoxin (streptozotocin and 5‐Fluorouracil) treatment

Imprint cytology specimens of metastases of intestinal carcinoids obtained by percutaneous biopsy were analysed cytofluorometrically with regard to nuclear DNA records. All untreated tumors (nine cases) exhibited diploid DNA values with a relatively low proliferative activity (less than 2% nuclei in Sphase region). The mean number of tetraploid cells was 5%. Cytofluorometry also was performed on five tumor metastases treated with the cytotoxin streptozotocin and 5‐fluorouracil. After treatment, an increase in the number of tetraploid cells (mean value, 30%) was noted, indicating that the cytotoxin treatment (possibly streptozotocin) on the tumor cells in vivo blocked progression from G2 to M phase. The current cytofluorometric analyses show that diploid nuclear DNA records and a low proliferative activity is a characteristic of malignant carcinoid tumors of the intestine. Due to regular DNA histograms in the carcinoid tumors, it is suggested that reliable studies are permitted of the effect of cytotoxins on the different phases of the cell cycle in vivo.