Flow cytometric analysis of the DNA content in primary and metastatic lesions of colorectal cancer

Relationship of Helicobacter pylori to Bcl-2 family expression, DNA content, and pathological characteristics of gastric cancer

BACKGROUND

Despite the fact that the association of Helicobacter pylori with an increased risk of gastric cancer has been well documented, the exact mechanisms of this association have not been fully elucidated. Scarce data on H. pylori infection and its relationship with the different pathological characteristics are available in Egypt.

AIM OF THE STUDY

The rationale of the present study was to determine the prevalence of H. pylori in a group of gastric cancer patients and to analyze the relationship between H. pylori infection with the different pathological characteristics including the types of gastric cancer and tumor location within the stomach, in addition, to investigate the Bcl-2 and Bax expressions along with DNA flow cytometric analysis in the gastric cancer patients with and without H. pylori infection.

METHODS

Samples were obtained from 66 consecutive patients with gastric cancer (46 males and 20 females). The youngest patient was 20 yr old, the oldest 76 yr with mean age of 52.8 yr. The samples were subjected for histopathological characterization, H. pylori detection, DNA flow cytometric analysis, and Bcl-2 and Bax expressions detection, in addition to apoptosis analysis.

RESULTS

The obtained results showed that the H. pylori infection was found in 38/66 (57.6%) [Odds ratio=1.357 with 95% confidence interval (CI) 0.84-2.2]. There was a statistical significance for Bcl-2, Bax, and apoptosis with H. pylori status (p = 0.009, 0.008, 0.032, respectively). On the other hand, There was a statistical significance for H. pylori infection with the disease grade (p = 0.015) and lymph node metastasis (p = 0.05). No statistical significance was found between H. pylori status with the patients' age, gender, tumor site, tumor type, depth of invasion, and stromal reaction.

CONCLUSIONS

These data may indicate that the H. pylori infection not only contributes in the disease formation through the apoptosis dysregulation but also takes a part in the disease dissemination and progression. In addition, it may reflect a biologic, pathogenic, and ethnic background affecting the relationship of H. pylori infection to gastric cancer in the Egyptian patients. A high rate of smoking in Egypt and the diet are important factors that may affect such background. Further studies are warranted.

Intratumor genetic heterogeneity in advanced human colorectal adenocarcinoma

Colorectal carcinogenesis is widely accepted as one of the best-characterized examples of stepwise progression. The existing colorectal carcinogenesis model assumes genetic homogeneity of individual tumors for the main known genetic alterations: K-ras and p53 genes point mutations and loss of heterozygosity (LOH) of chromosome 5q and 18q. The object of the present study was to demonstrate the existence of an intratumor genetic heterogeneity in advanced sporadic colorectal carcinoma for these genetic alterations. Using improved tissue microdissection and DNA extraction, for each tumor, amplifiable DNA was obtained from 15 to 20 areas, of which 1 to 2 concerned lymph node metastases (LNM). This study revealed that 10 of 15 (67%) analyzed tumors were heterogeneous for at least 1 genetic alteration, with between 2 and 6 genotypically different clones detected per tumor. No correlation was observed between the genotype of these subclones and histological differentiation or invasive propensity. Intratumor heterogeneity was more frequently observed for LOH than for point mutations, 67% and 58% for LOH at APC and DCC locus, and 20% for mutation of either the K-ras or p53 gene. In 5 of the 9 (56%) heterogeneous cases with available LNM, the genotype observed in the LNM was different from that of the main clone in the primary tumor, and moreover, 2 of the LNM displayed a genotype undetected in the primary tumor. In conclusion, intratumor genetic heterogeneity was demonstrated in advanced sporadic colorectal carcinoma and was represented as topographically distinct genotypic subclones. Taking into account such a significant genetic heterogeneity of colorectal tumors, the use of genetic markers for prognosis management should be reconsidered.

Extension of the frontiers of surgical indications in the treatment of liver metastases from colorectal cancer: long-term results

OBJECTIVE

To evaluate retrospectively the long-term results of an approach consisting of performing surgery in every patient in whom radical removal of all metastatic disease was technically feasible.

SUMMARY BACKGROUND DATA

The indications for surgical resection for liver metastases from colorectal cancer remain controversial. Several clinical risk factors have been reported to influence survival.

METHODS

Between March 1980 and December 1997, 235 patients underwent hepatic resection for metastatic colorectal cancer. Survival rates and disease-free survival as a function of clinical and pathologic determinants were examined retrospectively with univariate and multivariate analyses.

RESULTS

The overall 3-, 5-, 10-, and 15-year survival rates were 51%, 38%, 26%, and 24%, respectively. The stage of the primary tumor, lymph node metastasis, and multiple nodules were significantly associated with a poor prognosis in both univariate and multivariate analyses. Disease-free survival was significantly influenced by lymph node metastasis, a short interval between treatment of the primary and metastatic tumors, and a high preoperative level of carcinoembryonic antigen. The 10-year survival rate of patients with four or more nodules (29%) was better than that of patients with two or three nodules (16%), and similar to that of patients with a solitary lesion (32%).

CONCLUSIONS

Surgical resection is useful for treating liver metastases from colorectal cancer. Although multiple metastases significantly impaired the prognosis, the life expectancy of patients with four or more nodules mandates removal.

The effect of preoperative radiation therapy on glucose utilization and cell kinetics in patients with primary rectal carcinoma

BACKGROUND

Proliferating cells in neoplasms usually show rapid cell cycle times and high rates of glycolysis. Tumor glucose utilization (TuGluc), potential cell doubling time (Tpot), and the effect of radiotherapy (RT) were evaluated in patients with primary rectal carcinoma.

METHODS

2-[18F]-fluoro-2-deoxy-glucose (18F-FDG) was administered and dynamic positron emission tomography (PET) performed to determine TuGluc. Cell kinetics were measured with flow cytometry after labeling with iodo-deoxy-uridine. Two groups of patients were investigated prospectively: 1) those patients undergoing surgery only and 2) those patients undergoing surgery after receiving 30 gray of RT. Twenty consecutive patients with a cT3-NX-M0 tumor and age > 50 years were selected and randomized. One patient was excluded because of unexpected liver metastases and another had incomplete data.

RESULTS

At baseline, the TuGluc for Group 1 was 222+/-104 nmol/mL/minute (mean +/- 1 standard deviation), and was 215+/-126 nmol/mL/minute for Group 2 (P > 0.8). After RT TuGluc decreased to 77+/-39 nmol/mL/minute (P = 0.008). Tpot was 3.4+/-1.2 days for Group 1 and 2.6+/-2.0 days for Group 2 at baseline (P > 0.2). Two weeks after RT, Tpot slowed to 5.7+/-3.6 days (P = 0.04). A weak negative correlation (correlation coefficient = -0.36) was found between TuGluc and Tpot. After RT, the proportion of labeled cells had not changed from baseline levels (P > 0.2), suggesting undisturbed proliferation, but the DNA synthesis time had increased. The significant decrease of TuGluc indicated cell loss.

CONCLUSIONS

Tumor FDG uptake and cell kinetics are not correlated strongly in rectal carcinoma. Preoperative RT results in an overall loss of tumor cells (tumor reduction) and an increase in Tpot, although proliferation of the viable cell fraction is maintained.