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Early cellular events in colorectal carcinogenesis
A. G Renehan1, S. T O'Dwyer, N. J Haboubi
1Department of Surgery, Christie Hospital NHS Trust, Manchester, UK, Department of Histopathology, Trafford General Hospital, Manchester, UK, Epistem Ltd, Manchester, UK.
Summary
Aberrant crypt foci (ACFs) are now considered the earliest sign of colorectal cancer, surpassing traditional cell proliferation markers. Identifying and quantifying ACFs offers a more effective risk assessment for future cancer prevention studies.
Area of Science:
- Gastroenterology
- Oncology
- Cell Biology
Background:
- Colorectal cancer (CRC) progression is historically viewed through the adenoma-carcinoma sequence.
- Increased colonic crypt cell proliferation was long considered the earliest neoplastic event.
- This view is challenged by inconsistencies and the critical role of apoptosis in crypt homeostasis.
Purpose of the Study:
- To re-evaluate the earliest detectable events in colorectal carcinogenesis.
- To compare the efficacy of aberrant crypt foci (ACFs) versus crypt cell proliferation as early markers.
- To highlight ACFs as a superior intermediate marker for human risk assessment and chemoprevention studies.
Main Methods:
- Review and synthesis of existing human and animal studies on colorectal carcinogenesis.
- Histopathological analysis differentiating normal mucosa, aberrant crypt foci (ACFs), and adenomas.
- Evaluation of the ACF assay's utility in carcinogen detection and risk assessment.
Main Results:
- Aberrant crypt foci (ACFs), not increased crypt cell proliferation, are now recognized as the earliest step in colorectal carcinogenesis.
- Two types of ACFs exist: hypercellular and dysplastic, with dysplastic ACFs being most relevant to cancer development.
- ACFs can grow via crypt fission, forming microadenomas, and early lesions may be polyclonal.
Conclusions:
- Aberrant crypt foci (ACFs) represent the earliest pathological precursor in colorectal cancer development.
- The identification and quantification of ACFs provide a more effective intermediate marker for human risk assessment than crypt cell proliferation alone.
- The ACF assay holds significant potential for future cancer chemopreventive and risk assessment studies in humans.