家族性大腸腺腫症の外科的治療―予後からみた手術方針

Surgical Management of Familial Adenomatous Polyposis (FAP)

要旨　遺伝性腫瘍の研究と診療は，腫瘍一般の発生病理の解明に大きな手がかりを与えるとともに腫瘍体質の遺伝子診断，外科的，化学的癌予防法など対癌戦略に偉大な進歩をもたらした．FAPはその代表的疾患であるが患者は“癌と遺伝”という宿命的状況にある人々であり手厚い対策が急がれる．FAPそのほかの遺伝性腫瘍の対策は長期的な全体計画の下になされなければならず，外科療法はその一部にすぎない．したがって術式は結腸全摘回腸直腸吻合術（IRA），回腸肛門吻合術（IAA），回腸肛門管吻合術（IACA）のいずれを選ぶにせよ術後発現する腫瘍病変を早期に発見し，外科・内科的な予防対策を適切に行えるよう患者および家族の生涯追跡・監視，家系調査，遺伝子診断，カウンセリング，倫理，社会，法律的保護が行える体制の下に施行されるべきである．

　Hereditary tumors represented by familial adenomatous polyposis (FAP) has provided us with an opportunity to elucidate the etiopathegenesis of neoplastic disorders and to work out a new strategy towards cancer by presymptomatic molecular diagnosis, and medical and surgical prevention. Those patients and their families who are incidentally bear a heavy burden should receive an adequate medical care. At present a major part of the management of FAP is surgical prevention of colorectal cancer which could be fatal to the patient. An Indication for surgical prevention can be logically determined by the risk assessment which includes age, density of polyps and sex. A historical controversy on the preventive surgery for FAP, whether the rectum can be preserved or not, has been settled by the long-term follow-up study of restorative proctocolectomy. Currently, there are three surgical options for young patient with sparse polyposis without cancer, the IRA and treatment of polyposis in the remnant rectum when young followed by the delayed RPC in older age, the RPC with IAA or the RPC with IACA. All of them would be justified but only when performed by the specialists in the specific multidisciprinary centers for FAP or associated facilities where life long postoperative surveillance on the rectal and extracolonic lesions, extensive familial survey and authorized cooperative registration of those family members would be achieved. Surgery is, however, merely a prologue of a life long management of the FAP patients and their families under the specific cancer genetic strategy where the molecular diagnosis and computerized surveillance system would provide us more adequate treatment options including chemical prevention.