Heterogeneity in early and advanced gastric carcinomas by flow cytometric DNA analysis

DNA ploidy and its clinical implications in gastric cancer

BACKGROUND

Biological characteristics of gastric cancer depend mostly on genetic alterations in the cancer cells of individuals. To precisely predict the biological behavior and clinical outcome of individual cancer, it may be important to clarify the DNA profiles of cancer cells in each case.

METHODS

We have reviewed the most important results of studies on DNA ploidy of gastric cancer published in the English literature during the last 2 decades.

RESULTS

Gastric carcinoma with aneuploidy has been shown to have a high proliferative activity and a high metastatic or invasive potential, thus leading to a poor prognosis as compared to diploid tumors.

CONCLUSION

Analyses of DNA ploidy in gastric cancer may provide clinically useful information on diagnostic, therapeutic, and prognostic aspects. Further investigations may be needed to clarify the relationship between chromosome instability and DNA ploidy.

Progression of hepatocellular carcinoma as reflected by nuclear DNA ploidy and cellular differentiation

BACKGROUND/AIMS

Intratumor heterogeneity of DNA ploidy within a single hepatocellular carcinoma is not well understood. The present study was designed to examine the histologic distribution of intratumor DNA ploidy in hepatocellular carcinomas of different growth types in relation to cell differentiation.

METHODS

Twenty patients (16 men and four women; mean age, 60.2 years) with hepatocellular carcinoma (mean diameter, 4.3 cm) were studied. One hundred and twenty-seven samples from different sites of each tumor were analyzed by determination of the nuclear DNA content and histological examination.

RESULTS

The DNA ploidy was heterogeneous in nine (45%) of the 20 tumors. Five tumors had a mixture of diploid and aneuploid regions, and the remaining four consisted of aneuploid regions with different DNA indices. There was no significant difference in patient characteristics between the heterogeneous and homogeneous groups. A significant correlation was found between tumor growth type and the incidence of heterogeneity. Only 16% of single nodular carcinomas without intratumor septal formation exhibited heterogeneity, while single nodular tumors with septal formation or confluent multinodular tumors were associated with high incidences of different DNA ploidy patterns or DNA indices. There was no aneuploidy in well-differentiated foci, while aneuploidy was frequently found in moderately or poorly differentiated foci (incidences of 67% and 74%, respectively).

CONCLUSIONS

Heterogeneity of DNA ploidy may develop along with changes in growth pattern and cell dedifferentiation or by confluence of nodules originating from different tumor cell clones.

Flow cytometric analysis of variations in the DNA content of superficial and deep layers in colorectal cancer

We investigated variations in the DNA content of multiple samples from both superficial and deep layers of tumors from 81 colorectal cancer cases. The findings were only diploid in 21 cases (25.9%) and only aneuploid in 49 cases (60.5%). On the whole, the DNA ploidy agreed in 70 cases (86.4%) between both layers. In the 49 cases with only aneuploid tumors in both layers, the DNA index (mean +/- SD) was 1.58 +/- 0.25 in the superficial layer and 1.59 +/- 0.25 in the deep layer, with the values being almost identical. In contrast, a variation in the DNA ploidy of 11 cases (13.6%) was observed. These findings show that DNA ploidy remains stable during tumor progression from the superficial into the deep layers in most cases of colorectal cancer. However, the existence of heterogeneity in the DNA ploidy also shows that several specimens should be collected from both layers before making a determination of DNA ploidy.