大腸腺腫症―最近の知見と臨床

Clinical Features of Familial Adenomatous Polyposis: Genotype-phenotype Correlation and Chemoprevention

要旨　家族性大腸腺腫症において，大腸腺腫の数により分類された，密生型，非密生型，および散発型の表現型の違いは大腸癌発生の年齢と相関するが，それぞれAPC遺伝子の変異部位，すなわち遺伝型との関連が認められている．大腸外病変でも網膜色素上皮肥大やデスモイド腫瘍など，遺伝型との関連が認められるものもある．一方，大腸腺腫，デスモイド腫瘍に対しsulindacが効果を示す．投与6か月後には残存直腸の腺腫の消失をみ，また，デスモイド腫瘍も縮小する．遺伝型を考えたサーベイランスを行い，sulindacによるchemopreventionを併用することにより，術後の予後，QOLを向上させる可能性がある．

　According to the number of colorectal adenomas, familial adenomatous polyposis is classified under three phenotypes; profuse type, sparse type and attenuated type. The mean age of diagnosed polyposis, cancer and of death differs depending on which type is present. Each phenotype has a relationship with a certain mutation on the APC gene. Some of the extra colonic manifestations, such as desmoid tumor and hypertrophy of the retinal pigment epithelium also have a certain relationship with a specific mutation.

　Sulindac induces regression of colorectal adenomas. The number and size of adenomas were reduced after 6 months administration of sulindac. Desmoid tumor is also reduced by sulindac therapy.

　Both genotype-phenotype correlation and sulindac chemoprevention are important for managing patients so that they wont develop desmoid tumor and tumor of the residual rectum.