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Hereditary nonpolyposis colorectal cancer
1Creighton University School of Medicine, Omaha, Nebraska, USA. htlynch@creighton.edu
Seminars in Surgical Oncology
|May 11, 2000
Summary
Lynch syndrome, the most common hereditary colorectal cancer (CRC), is diagnosed via cancer family history and genetic mutations like hMSH2 and hMLH1. Understanding its natural history is crucial for effective patient management and screening.
Area of Science:
- Oncology
- Genetics
- Gastroenterology
Background:
- Hereditary nonpolyposis colorectal cancer (HNPCC), known as Lynch syndrome, is the predominant form of hereditary colorectal cancer (CRC).
- Unlike familial adenomatous polyposis (FAP), Lynch syndrome lacks distinct clinical markers, making cancer family history critical for diagnosis.
- Germ-line mutations, primarily in hMSH2 and hMLH1, identified in the 1990s, significantly enhanced Lynch syndrome diagnosis.
Purpose of the Study:
- To emphasize the importance of cancer family history in diagnosing Lynch syndrome.
- To highlight the role of genetic discoveries in improving diagnostic capabilities.
- To underscore the necessity of understanding the natural history of Lynch syndrome for effective medical management.
Main Methods:
- Diagnosis relies on detailed cancer family history.
- Identification of germ-line mutations (hMSH2, hMLH1) aids in diagnosis.
- Understanding the natural history informs management strategies.
Main Results:
- Approximately 70% of CRCs in Lynch syndrome occur proximal to the splenic flexure, with a significant proportion in the cecum.
- A high incidence of metachronous CRCs necessitates consideration of subtotal colectomy for initial CRC management.
- Genetic counseling and patient/physician education are vital for compliance with testing, screening, and management.
Conclusions:
- Accurate diagnosis of Lynch syndrome depends on comprehensive family history and genetic testing.
- Management strategies must account for the specific natural history of Lynch syndrome, including tumor location and risk of metachronous cancers.
- Effective patient care requires informed decision-making through genetic counseling and education for both patients and physicians regarding genetic risk.