Lynch syndrome: clinical, pathological, and genetic insights

Endometrial cancer and microsatellite instability status

Microsatellite instability (MSI) is an important factor in the development of various cancers as an identifier of a defective DNA mismatch repair system. The objective of our study was to define the association between microsatellite instability status and traditional clinicopathologic characteristics of endometrioid type adenocarcinoma.

Clinical significance of microsatellite instability in colorectal cancer

INTRODUCTION

Colorectal cancer is a heterogeneous tumor type with regard to molecular pathogenesis and genetic instability. The majority of colorectal cancers display chromosomal instability and follow the classical adenoma-carcinoma sequence of tumor progression. A subset of about 15 % of colorectal cancers, however, displays DNA mismatch repair (MMR) deficiency and the high-level microsatellite instability (MSI-H) phenotype. MSI-H colorectal cancers can occur as sporadic tumors or in the context of hereditary non-polyposis colorectal cancer (HNPCC) or Lynch syndrome.

CLINICAL RELEVANCE

The MSI-H phenotype is a hallmark of Lynch syndrome-associated cancers, which is of diagnostic relevance for the identification of Lynch syndrome mutation carriers. MSI-H colorectal cancers are characterized by a distinct clinical behavior, which results from their particular molecular pathogenesis and gives microsatellite instability testing its clinical significance. The MSI-H phenotype shows association with proximal tumor localization, a dense local lymphocyte infiltration, and a low frequency of distant organ metastasis. Moreover, MSI-H colorectal cancers have a better prognosis than their microsatellite-stable counterparts. A distinct responsiveness of MSI-H colorectal cancer patients towards chemotherapy has been shown in several studies.

CONCLUSIONS

The clinical characteristics of MSI-H cancers are closely linked to their molecular pathogenesis, and research on the molecular alteration characteristic of MSI-H cancers may provide the basis for novel diagnostic or therapeutic approaches.

[Aspirin and prevention of colorectal carcinomas]

Observational and some randomized clinical trials suggest that aspirin protects from occurrence and progression of colorectal neoplasias (adenomas, carcinomas). However, there are still open questions, regarding the benefit/risk ratio (bleedings) as well as dosage and duration of treatment during the probably long-term medication, before stringent recommendations regarding clinical use of aspirin can be made. Specifically, there is currently no generally accepted mode of action or molecular target of aspirin, though a relationship to tumor-associated enhanced PGE2 levels in the affected mucosa is likely. Regular daily intake of aspirin in antiplatelet doses of 100 mg appears to be sufficient in responding persons. If this is confirmed in prospective randomized trials that are currently underway, this might add to the prophylactic use of aspirin and would suggest a pharmacological relationship to inhibition of COX-1 mediated prostaglandin/thromboxane biosynthesis as a common primary target for both cardiocoronary and antineoplastic prophylaxis. Prophylactic aspirin use might then add to an undoubtedly important healthy lifestyle including appropriate diet.

Colorectal carcinoma: Pathologic aspects

Colorectal carcinoma is one of the most common cancers and one of the leading causes of cancer-related death in the United States. Pathologic examination of biopsy, polypectomy and resection specimens is crucial to appropriate patient managemnt, prognosis assessment and family counseling. Molecular testing plays an increasingly important role in the era of personalized medicine. This review article focuses on the histopathology and molecular pathology of colorectal carcinoma and its precursor lesions, with an emphasis on their clinical relevance.

Colorectal carcinoma: Pathologic aspects

Colorectal carcinoma is one of the most common cancers and one of the leading causes of cancer-related death in the United States. Pathologic examination of biopsy, polypectomy and resection specimens is crucial to appropriate patient managemnt, prognosis assessment and family counseling. Molecular testing plays an increasingly important role in the era of personalized medicine. This review article focuses on the histopathology and molecular pathology of colorectal carcinoma and its precursor lesions, with an emphasis on their clinical relevance.