Flow cytometric analysis of DNA content in gastric and colorectal cancer

Analysis of DNA ploidy and proliferative activity by flow cytometry (FCM) of gastric (GC) and colorectal cancer with morphology (histology and cytology) and prognostic correlation was performed.

The study group consisted of 160 patients with GC (93) and colorectal cancer (CRC) (67). Tumor samples were taken by gastric and colon biopsy. All patients subsequently underwent surgery. DNA content was assessed using an ICP II cytometer (Phywe, Germany). Two samples were taken from the tumor, one for cytology and FCM and the other for histology. Macroscopically, unchanged mucosa served as a control group. Three types of DNA histogram were distinguished in accordance with the ploidy and proliferative activity of the tumor.

The number of aneuploid and diploid tumors was the same in GC and CRC and reached 53% (49/93) and 66% (44/67), respectively (P > .05). Morphologic study discovered predominance of adenocarcinoma in both GC and CRC, with mainly poor differentiation (53/93) in GC and moderate and high differentiation in CRC (49/67). There was a large group of signet-ring cell GCs (18, 19.4%), while in CRC this was diagnosed in 4 (6.0%) cases only. Poorly differentiated adenocarcinomas were significantly more frequent among aneuploid tumors (41/49 in GC and 13/44 in CRC) than among diploid tumors (12/44 in GC and 0/23 in CRC). Five-year survival in GC (89) and CRC (64) strongly correlated with DNA histogram type. Survival was the highest in patients with DNA histogram type I (diploid tumor and poor proliferative activity). The poorest prognosis was associated with aneuploidy and high proliferative activity of cells (DNA histogram type III).

The differences between DNA histogram types indicate that survival depends to a greater degree upon proliferative activity of tumor cells than upon tumor ploidy.