[Feasibility of DNA analysis for prognostic evaluations of colorectal cancer using touch preparations and image cytometry].

The purpose of this study is to demonstrate the applicability of DNA ploidy analysis by using touch preparations obtained from fresh and frozen tissues on the prognostic evaluations of colorectal cancer, especially the development of hepatic metastases. The specimens obtained from surgically resected colorectal carcinomas (32), and hepatic metastases (4), were lightly touched with the slide glasses. Among the 32 patients with colorectal cancers, 7 had synchronous liver metastases, and 5 metastases developed metachronously. After formalin-fixation and Feulgen staining, the DNA analysis was performed by image cytometer (ICM, CAS200R). The data were expressed as the ploidy patterns and DNA indices (p-DNAI: peak DNA index, m-DNAI: mean DNA index), and were correlated very well with those obtained from cytophotometry. The DNA ploidy pattern among the 32 colorectal cancer specimens were Aneuploid(A) in 16, Polyploid (P) in 7, Diploid (D) in 4 and D+P in 5. The cases with synchronous or metachronous liver metastases had a higher m-DNAI (1.74 +/- 0.28) and were Aneuploid in 8, P in 3, and D+P in 1 case. Aneuploidy or Polyploidy predominated among the cases with metachronous liver metastases (4 in 5 cases), with m-DNAI higher than 1.5. Thus, "m-DNA > 1.5" could be a useful prognostic indicator of the high risk group of liver metastases. The liver metastases specimens had Aneuploid and Polyploid patterns in 2 cases each, with m-DNAI ranging from 1.88 to 2.31. DNA ploidy pattern analysis using touch preparations with image cytometry may be useful in determining the prognosis for colorectal cancer.