| 特集名 | 下部消化管の前癌病変，高発癌状態をめぐって | |
|---|---|---|
| 題名 | 大腸前癌病変と分子生物学的変化 | |
| 発刊年月 | 2010年 09月 | |
| 著者 | 澤田 武 | 聖マリアンナ医科大学消化器・肝臓内科 |
| 著者 | 伊東 文生 | 聖マリアンナ医科大学消化器・肝臓内科 |
| 【 要旨 】 | 従来，大腸癌発生のおもな経路として，腺腫を介したadenoma-carcinoma sequenceが提唱されてきた．同経路は多段階発癌のモデルとされ，染色体の欠失，増幅などを伴うことより染色体不安定性発癌とも呼ばれる．一方，ゲノムワイドなメチル化の異常であるCpG island methylator phenotypeにより，マイクロサテライト不安定性を伴い発癌する経路が報告された．前癌病変は鋸歯状病変と考えられるため，同経路はserrated-neoplasia pathwayと呼ばれる．分子生物学的な分類では，絨毛状腺腫を介した別の経路の存在も示唆されており，さらなる研究の進歩が期待される． | |
| Theme | Precancerous Conditions and Cancer High-risk Lesions in the Colorectum | |
|---|---|---|
| Title | Precursor Lesions of Colorectal Cancer and Associated Molecular Changes | |
| Author | Takeshi Sawada | Division of Gastroenterology and Hepatology, St. Marianna University School of Medicine |
| Author | Fumio Itoh | Division of Gastroenterology and Hepatology, St. Marianna University School of Medicine |
| [ Summary ] | Recent advances in molecular genetics have shown that colorectal cancer (CRC) is a heterogeneous disease which develops through diverse molecular pathways. The adenoma-carcinoma sequence (chromosomal instability pathway), caused by sequential accumulations of mutations in oncogenes and tumor suppressor genes (such as APC, Kras, p 53) has been proposed as a genetic model for CRC. However, a subset of sporadic CRCs exhibit both high levels of microsatellite instability and methylation of multiple CpG islands, a phenomenon known as CpG island methylator phenotype. This CRC subset pathway is called the "serrated-neoplasia pathway" because its precursor lesions are typically serrated. Additionally, classification of CRC based on integrated genetic and epigenetic analysis suggests the presence of another distinct subclass. Although the third subclass is heterogeneous, the prognosis is worse, with lower responsiveness to chemotherapy. This subclass may arise from villous adenomas, but perhaps also from serrated adenomas. We also describe genetic and epigenetic changes in hereditary non-polyposis colon cancer, familial adenomatous polyposis and MYH-associated polyposis. |
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