Chromosome studies of solid tumours

VEGFA locus amplification potentially predicts a favorable prognosis in gastric adenocarcinoma

Gastric adenocarcinoma harbors a range of genetic and epigenetic alterations, including alterations in DNA copy number. However, the key genes that promote the development and progression of gastric adenocarcinoma remain unknown. To identify the key genes amplified in gastric adenocarcinoma, we performed array comparative genomic hybridization on formalin-fixed paraffin-embedded samples of surgically resected gastric adenocarcinoma. We detected a relatively wide genomic region of gain containing the vascular endothelial growth factor A (VEGFA) gene locus on chromosome 6p. VEGFA locus amplification in gastric adenocarcinoma was validated by fluorescence in situ hybridization. To assess the frequency of VEGFA locus amplification in gastric adenocarcinoma, we conducted multiplex ligation-dependent probe amplification (MLPA) assays using homemade probes designed to target the VEGFA gene locus. Eleven of 54 (20 %) gastric adenocarcinomas with MLPA values above 1.3 were defined as having VEGFA locus amplification. Next, we investigated the effect of VEGFA locus amplification on the clinicopathological characteristics of gastric adenocarcinomas and patient survival. VEGFA locus amplification demonstrated a significantly close relationship with pathological intestinal type and lower rates of venous invasion Furthermore, a Kaplan-Meier analysis showed that patients with VEGFA locus amplification had significantly better overall survival than those without amplification (p = 0.038), particularly in the long-term follow-up period. In conclusion, VEGFA locus amplification can predict modest aggressiveness and good outcomes, suggesting the possibility that it may predict a favorable prognosis in patients with gastric adenocarcinoma.

Treatment of chronic myelogenous leukemia as a paradigm for solid tumors: how targeted agents in newly diagnosed disease transformed outcomes

Although chronic myelogenous leukemia (CML) is rare, with approximately 5000 new cases in the United States annually, it may be the poster child for the future of oncology. Imatinib mesylate, a selective Bcr-Abl tyrosine kinase inhibitor (TKI), transformed the course of CML from a rapidly fatal disease (median survival, 3 to 6 years) to a functionally curable, indolent disease with an estimated median survival of more than 25 years. This transformation can be attributed to several key factors: the identification of a causal and actionable molecular aberration-BCR-ABL; the development of a potent and selective Bcr-Abl TKI-imatinib; and, importantly the application of imatinib in the earliest phase of CML. In contrast, imatinib, if used in CML blastic phase, improves median survival to only about 1 year. Similar to CML blastic phase, metastatic solid malignancies have undergone genetic evolution, and their molecular aberrations are complex. As a result, resistance is common and eradication is difficult. The key to the dramatic improvement in the survival of patients with CML involved using imatinib in newly diagnosed disease, before blastic transformation. We hypothesize that metastatic solid tumors are analogous to CML blastic phase, and that to achieve improvements in solid tumor outcomes similar to those seen in CML, application of targeted agents to newly diagnosed disease may be required to prevent disease transformation (i.e., metastases). Targeting driver mutations at the time of diagnosis may be critical to the goal of markedly changing the outlook for patients with cancer.

Detection of trisomy 7 with fluorescence in situ hybridization and its correlation with DNA content and proliferating cell nuclear antigen-positivity in prostate cancer

The authors applied fluorescence in situ hybridization (FISH), using specific DNA probes for chromosome 7, to routine paraffin-embedded tissue sections obtained from 35 radical-prostatectomy specimens. Proliferative activity was also evaluated using static cytometry to assess DNA content and immunohistochemistry for proliferating cell nuclear antigen (PCNA) positivity. These results were correlated with each other and with the morphologic parameters. The presence of three or more of chromosome 7 was observed in 71% of the cases, as was a high S phase, with a triploid prevalent DNA content and a PCNA index above mean value in 66% of the cases. No correlation was detected between these findings and histologic grade; conversely, there was a significant correlation with stage (chi-square = 5.33; p = 0.021). From these results, the authors maintain that the presence of an extra chromosome 7-correlated in most cases with an increase in cell kinetics and an advanced stage-may be an additional prognostic marker of aggressive behavior.

Frequency of atypical mitosis in intestinal metaplasia of the gastric mucosa in Japanese patients

The morphologic characteristics of the mitotic figures present in intestinal metaplasia (IM) of the gastric mucosa were investigated in 70 consecutive gastrectomy specimens from Japanese nationals. The specimens contained, in addition, early gastric cancer of intestinal type (n = 44) or of diffuse type (n = 22). The remaining 4 were recorded as mixed. One hundred or more consecutive mitoses/specimens were studied by high-power microscopy in hematoxylin and eosin-stained preparations (at x1000). A total of 7259 mitoses were recorded (mean 103.7 mitoses/case). Of these, 1089 mitoses (i.e. 19.1%) were considered as atypical according to a previous classification. The percentage of atypical mitoses was found to be unrelated to the gender, to the increasing age of the patients, to the histologic type of the adenocarcinoma contained in the specimens, or to the anatomic site (e.g. corpus or antrum or tumor proximity). Comparative studies were done with gastrectomy specimens from Swedish nationals (a population with a 4-times-lower incidence of gastric carcinoma than the Japanese). The results showed a much lower frequency of mitotic figures/specimen and only occasional atypical mitosis. Since atypical mitosis has so far been reported only for neoplastic lesions in the gastrointestinal tract, it is suggested that IM with atypical mitosis may be a genuine precancerous lesion in the gastric mucosa in Japanese subjects.