一起聊聊关于家族性腺瘤性息肉病

家族性腺瘤性息肉病简称为 FAP (familial adenomatous polyposis)。家族性腺瘤性息肉病（FAP）是一种常染色体显性遗传性疾病，表现为整个结直肠（大肠）布满大小不一的腺瘤。多在15岁前后出现息肉，初起时息肉为数不多，随着年龄增长而增多。中国科学技术大学附属第一医院(安徽省立医院)肿瘤科何义富

FAP是遗传性疾病 一旦有一个病人发病，其子女就有50%的可能性遗传疾病。约2/3的FAP患者来自父母遗传，而患者的兄弟姐妹也有一半机会得FAP。其余1/3的FAP 患者并不是遗传自父母，原因是由于新的基因突变而引发的。FAP病人的家属需要通过结肠镜检查进行筛查，一旦发现出现FAP应尽早手术切除，以免随着时间的延长而发生癌变。FAP会演变成大肠癌吗？如果未及时治疗，FAP患者的大肠息肉几乎100%发生癌变。FAP引起的结直肠癌约占所有结直肠癌患者的1%，病人在出生时并无结直肠息肉，多数在15岁前后出现息肉，初起时息肉为数不多，随着年龄增长而增多，在病人青少年期整个大肠有成百上千个，息肉越大越容易发生癌变。FAP的息肉大多在30多岁时发生癌变，未治疗者平均死亡年龄在42岁左右。常见症状：腹痛，腹泻或便频、便稀，便血，消瘦、贫血、乏力。

FAP出现症状的年龄为20岁，发现癌变的平均年龄为35-40岁，20岁左右出现癌变者为数极少，因此理想的手术时间在20岁以前，一旦确诊，应立即行手术治疗。全大肠切除+末端回肠造口术、全结肠切除+回肠直肠吻合术、全大肠切除+回肠储袋肛管吻合术。具体术式及手术时机还需结合患者具体病情进行综合考虑。对于一些年轻尚未生育，而且直肠息肉较少者，可以考虑保留部分直肠，然后定期随访将发现的息肉摘除，这样对性功能和大小便功能的影响较小，而且效果也较好。

基因测试能够检验APC的突变基因，帮助诊断。方法安全简单，只需为病人抽取20毫升的血液则可。当结果为阳性时，我们便可借着结果，在病人的家人同意下，也可让FAP患者尽早进行治疗，采取适当的癌症预防措施。在适当的治疗和预防方法下，大多数FAP患者的寿命与一般人无异。

FAP高危人群通常需要从10～15岁开始进行每年的肠镜监测，直至35岁，然后每3年检查一次。基因检测是十分重要的，如果APC基因存在，50％先前的高危人群其实没有从父母遗传突变，而即使存在MYH基因，其发生FAP的几率也是低的（需要父母双方携带MYH突变基因）。肠外检查如女性患者的甲状腺检查也应包括。在随诊中，可综合运用各种检查和分析方法，如体检、结肠镜检、眼科检查、牙齿和下颌骨放射学检查、分子遗传学检测等。IPAA和IRA术后应每3至6个月检查一次肠镜，对于直肠腺瘤可以在内镜下消融，如果腺瘤无法用消融或化学预防，则考虑手术切除直肠。

Familial adenomatous polyposis (FAP) is an autosomal dominant inherited condition in which numerous adenomatous polyps form mainly in the epithelium of the large intestine. While these polyps start out benign, malignant transformation into colon cancer occurs when they are left untreated. Three variants are known to exist, FAP and attenuated FAP (originally called hereditary flat adenoma syndrome[1]) are caused by APC gene defects on chromosome 5 while autosomal recessive FAP (or MUTYH-associated polyposis) is caused by defects in the MUTYH gene on chromosome 1. Of the three, FAP itself is the most severe and most common; although for all three, the resulting colonic polyps and cancers are initially confined to the colon wall. Detection and removal before metastasis outside the colon can greatly reduce and in many cases eliminate the spread of cancer.

The root cause of FAP is understood to be a genetic mutation—a change in the body's tumour suppressor genes that prevent development of tumours. The change allows numerous cells of the intestinal wall to develop into potentially cancerous polyps when they would usually reach the end of their life; inevitably one or more will eventually progress and give rise to cancer (7% risk by age 21, rising to 87% by age 45 and 93% by age 50). These gene changes do not trigger cancer, but rather, they reduce the body's ability to prevent cells from becoming cancerous. Even with the gene change, it may still take time before a cell actually does develop that is cancerous as a result, and the gene may in some cases still partially operate to control tumours, therefore cancer from FAP takes many years to develop and is almost always an adult-onset disease.