Loss of constitutional heterozygosity in human astrocytomas

Genetic instability and mutation of the TGF-beta-receptor-II gene in ampullary carcinomas

Ampullary carcinomas are relatively rare cancers of which very little is known in terms of carcinogenetic mechanisms at the molecular level. Genetic instability caused by mutations of mismatch-repair genes has been demonstrated to be responsible for hereditary non-polyposis colorectal cancers and a sub-set of sporadic colorectal cancers. In some of those tumors showing genetic instability, the transforming-growth-factor-beta(TGF-beta)-receptor-II gene has been found to be mutated in repetitive sequences and considered to be a target of replication error. We studied the role of genetic instability and associated TGF-beta-receptor-II-gene mutations in a series of 18 sporadic cases by analyzing 5 microsatellite loci (D2S123, D3S1029, D5S409, TP53 and BAT26) and by sequencing a poly-A repeat (nucleotides 709-718) in the TGF-beta-receptor-II gene. Microsatellite instability was observed in 4 (22.2%) and gene mutations in 14 (77.8%) cases. These data indicate that the TGF-beta-receptor-II gene might be a preferential target of genetic instability whose alteration might be specifically advantageous and constitute a common step in the development of ampullary carcinomas.

Molecular pathogenesis of astrocytoma and glioblastoma multiforme

Our understanding of the complexity of genetic abnormalities involved in the tumourigenesis of malignant gliomas is as yet rudimentary. However, we can discern distinctive patterns of loss of genetic material and amplification of chromosomal regions that characterize both the different types of gliomas as well as the different malignancy grades. In this review, we discuss through specific examples of recent work on astrocytomas and glioblastoma multiforme, the importance of several tumour suppressor genes and oncogenes in the development of these glial tumours. In conclusion it would seem that distinct genetic changes in different genes, the protein products of which interact in particular growth control mechanism may lead to the same cellular abnormality. It seems likely that many further genetic abnormalities affecting genes coding for proteins, either involved in the cellular mechanisms yet identified or in new growth control mechanisms. Will be found in the near future.

Prognostic factors in low-grade supratentorial astrocytomas: a uni-multivariate statistical analysis in 76 surgically treated adult patients

A retrospective uni-multivariate statistical analysis was performed on 32 prognostic factors to investigate their importance in predicting survival in a series of 76 adult patients with low-grade supratentorial astrocytomas treated over a 13-year period. The end point used for this study was the length of survival. The median survival time was 40 months. Overall actuarial survival at 2, 5, and 10 years was 69%, 38%, and 22%, respectively. Radical resection of the neoformation, a higher preoperative Karnofsky performance status (KPS) score, and an age younger than 50 years are strongly correlated with survival; postoperative radiotherapy appears to be associated with increased survival only in patients under 50 years of age.