新規Lynch症候群患者の拾い上げと診断後のサーベイランスの実践

How to Identify Individuals at Risk for Lynch Syndrome and How to Perform Colonoscopic Surveillance

要旨　Lynch症候群はミスマッチ修復遺伝子の生殖細胞系列異常による，発癌リスクの高い疾患群である．患者，家系内に大腸癌・子宮内膜癌・胃癌など，多種多様な癌が発生し，特徴的な病態を示す．しかしながら，一般臨床における認知度はいまだ低く，診断に至らない潜在的な患者の拾い上げが課題である．本稿では，Lynch症候群患者における大腸癌の臨床的特徴につき概説し，さらに，患者の拾い上げの実際，確定診断に至る過程，その後のサーベイランスなど，実臨床に則したLynch症候群患者の診療について述べる．

　Lynch syndrome is an autosomal dominant genetic disorder caused by germline mutations in DNA MMR（mismatch repair）genes. The syndrome is associated with a high risk of developing various cancers, in particular colorectal, endometrial, and gastric cancer. However, awareness regarding Lynch syndrome is limited among general clinicians, hence patients with Lynch syndrome are often not diagnosed.

　In this review, we will focus on the clinical features of colorectal cancer in Lynch syndrome patients. In addition, we will discuss practical ways of screening to detect this syndrome, leading to improved diagnosis and surveillance.