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Molecular genetic alterations as potential prognostic indicators in colorectal carcinoma
1Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
Abstract:
The molecular genetic alterations in colorectal carcinoma are among the best understood of any common human cancer. Identified abnormalities include both dominant-acting oncogenes (ras, myc, src) and suppressor genes which undergo inactivation or deletion (deleted in colorectal carcinoma gene [DCC], p53, adenomatous polyposis coli gene [APC], and probably loci on chromosomes 1p and 22q). Accumulation of multiple abnormalities is evident in the adenoma-carcinoma sequence with a preferential order, and alteration of DNA methylation is an especially early event. Identification of molecular genetic markers useful for classification and staging of colorectal carcinoma is in its infancy. Deletion of the p53 gene on chromosome 17p, deletion of the DCC gene on 18q, and high fractional allelic loss (fraction of evaluable nonacrocentric autosomal arms with deletion) have been associated with distant metastases and with poorer prognosis in patients without initial evidence of disseminated disease. Additional studies are needed to determine the possible role of these alterations in clinical management.
Insights
Molecular genetic alterations in colorectal cancer, including oncogenes and suppressor genes, are well-understood. Specific gene deletions are linked to metastasis and poorer prognosis, aiding potential clinical management strategies.
Area of Science:
- Oncology
- Molecular Genetics
- Cancer Biology
Background:
- Colorectal carcinoma (CRC) molecular genetics is extensively studied.
- Key genetic alterations involve oncogenes (e.g., ras, myc, src) and tumor suppressor genes (e.g., DCC, p53, APC).
- Genetic changes accumulate during the adenoma-carcinoma sequence, with DNA methylation alterations occurring early.
Purpose of the Study:
- To review the current understanding of molecular genetic alterations in colorectal carcinoma.
- To explore the potential of molecular markers for CRC classification and staging.
- To investigate the prognostic significance of specific genetic alterations.
Main Methods:
- Review of identified molecular genetic abnormalities in CRC.
- Analysis of gene inactivation/deletion patterns.
- Association of genetic markers with clinical outcomes such as metastasis and prognosis.
Main Results:
- Multiple genetic abnormalities accumulate progressively in CRC development.
- Deletion of p53 (17p), DCC (18q), and high fractional allelic loss correlate with distant metastases.
- These genetic alterations are associated with poorer prognosis, even in patients without initial evidence of disseminated disease.
Conclusions:
- Specific molecular genetic alterations in CRC have prognostic implications.
- Further research is needed to integrate these markers into clinical management.
- Molecular markers hold promise for improving CRC classification and staging.