Familial Adenomatous Polyposis

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Familial Adenomatous Polyposis 1 in 10,000 incidence 100 s to 1000 s of colonic adenomas by teens Cancer risk: colon, gastric, duodenum (periampulla), small bowel, pancreas,

2 Familial Adenomatous Polyposis 1 in 10,000 incidence 100 s to 1000 s of colonic adenomas by teens Cancer risk: colon, gastric, duodenum (periampulla), small bowel, pancreas, papillary thyroid, childhood hepatoblastoma 7% risk of CRC by 21 yrs; 93% by 50 yrs Autosomal dominant: APC gene mutations Variants: Gardner (extracolonic), Turcot (medulloblastoma)

4 FAMILIAL ADENOMATOUS POLYPOSIS

5 Inherited Polyposes FAP/Gardners

6 NORMAL MUCOSA

7 HYPERPLASTIC POLYP LINED BY BENIGN EPITHELIUM

8 TUBULOVILLOUS ADENOMA

9 INVASIVE ADENOCARCINOMA

10 Rectal zone Sigmoid colon apple core lesion of distal sigmoid:

11 Inherited Polyposes FAP/Gardners Associated with mutation of the adenomatous polyposis coli (APC) gene on chromosome 5 - encodes tumor suppressor gene Polyps appear usually in the second or third decade; malignant changes have occurred as young as 9 years of age Polyps are typically small and sessile; endoscopic resection difficult because of huge numbers

12 Inherited Polyposes FAP/Gardners Association with osteomas (skull), desmoids (intra-abdominal), or epidermoid cysts, along with small bowel tumors (those in duodenum have high malignant potential) : Gardners Association with medulloblastoma or glioblastoma : Turcots Each of the above shares the genetic defect with FAP.

17 Polyps and tumors Colon: Adenomas, less than 1 cm, multiple, numbers may correlate with site of mutation Gastric: Fundic retention polyps - - no malignant potential Adenomatous polyps probably malignant potential but no increased gastric Ca risk Duodenum clustered around papilla found in 33-92% FAP patients Spigelman staging suggests therapy Desmoids Not malignant but may be nasty Usually in mesentery, also abdominal wall and extremities Occur in 10% - cause of death in 1%

18 Other FAP stuff Osteomas - usually mandible Epidermoid, sebaceous cysts Fibromas, lipomas CHRPE retinal lesions asymptomatic correlates with mutation

increases with number of adenomas If untreated 100%

19 Natural History Adenomas begin to develop in early adolescence colorectal adenomas Cancer risk increases with number of adenomas If untreated 100% colorectal cancer risk Median life expectancy 42 years

20 FAP surveillance Colon Annual sigmoidoscopy, age yrs Prophylactic colectomy following polyp detection w/continued surveillance of rectum, ileal pouch Duodenal/gastric EGD age 25, repeat 1-3 yrs Thyroid Annual PE, age 10 Hepatoblastoma Annual screen by abd U/S & AFP from birth to 5 yrs. Gastroenterology 2001; 121: 195. AGA Statement

21 Inherited Polyposes FAP/Gardners Affected proband should have genetic testing - disease is inherited in autosomal dominant fashion If defect is identified in proband, family members can also be screened to identify those at risk Otherwise, children should begin screening with annual flexible sigmoidoscopy by age Dx: > 100 POLYPS Surgery: > 5 mm, > 6-9 per cm 2. Timing in others is controversial; post op need screening EGD s

22 Genetic Testing: FAP/AFAP Test an affected family member first! After genetic counseling and informed consent APC gene testing can confirm a suspected diagnosis Family members of a person with a known APC mutation can have mutation-specific testing Genetic testing for children at risk for FAP can be considered before beginning colon screening

23 Inherited Polyposes FAP/Gardners Sulindac: In a variety of animal studies, NSAIDs have been shown to decrease tumor growth In early human FAP trials, sulindac caused tumor regression. This effect replicated in subsequent randomized, placebo controlled, double-blinded trials Problems: Tumors recur when drug stopped Side effects limit utility; specific COX 2 inhibitors needed

24 Attenuated FAP 20 to 100 polyps, usually more proximal Onset later than FAP, average AOO = 50 Lifetime risk of CRC = 80% Extracolonic tumors occur at same rate as FAP Variant of FAP, mutations in same APC gene Surveillance: annual colonoscopy starting late teens or early 20 s Option of subtotal colectomy

25 APC gene mutation in Ashkenazi Jews Missense mutation (I1307K) associated with increased risk of CRC and adenomas in Ashkenazi Jews (AJ) Found in 6% of the general AJ population 12% of AJs with CRC 29% of AJs with CRC and a positive family history Lifetime risk of CRC in mutation carrier is 10-20% Screening: colonscopy every 2-5 yrs starting at 35 yrs

26 MAP syndrome/myh gene Multiple adenomatous polyposis (MAP) syndrome Autosomal recessive; mutations in the MYH gene Median number of polyps = 55 Mean age of polyp diagnosis = years Polyps mainly small, mildly dysplastic tubular adenomas. Some tubulovillous, hyperplastic, serrated adenomas, microadenomas 30% of individuals with polyps have homozygous mutations in the MYH gene Genetic testing should be offered if >15 polyps (and APC gene testing negative)

27 Peutz-Jeghers syndrome <1% of all CRC cases Hamartomatous polyps of GI tract as early as 1 st decade Mucocutaneous hyperpigmentation lips, mouth, buccal mucosa, fingers Usually seen in children < 5 yrs Cancer risk: colon, small intestine, stomach, pancreas, breast, ovaries, uterus, testes, lungs, kidneys Mutations in STK11 gene found in 70% of familial cases and 30-70% of sporadic cases

29 Inherited Polyposes Peutz-Jeghers Hamartomatous polyps associated with mucocutaneous pigmentation. Brown-black freckles involving lips, oral mucosa and other sites - may fade with age Polyps, 1-3 cm in size, involve jejunum, colon, stomach and duodenum Sx: abdominal pain (intussusception), anemia Risk of Ca (18 fold increase) of duodenum/stomach, small bowel, and ovary

30 Inherited Polyposes Peutz-Jeghers Fundic or duodenal polyps should be removed promptly because of malignant potential Female patients should have periodic pevic examinations Genetic lesion: serine/threonine kinase, located 19p13.3 (most families)

34 Peutz-Jegher

35 Familial Juvenile Polyposis <1% of all CRC cases Autosomal dominant 5 or more juvenile polyps in colon or GI tract Appear in 1 st or 2 nd decade 50% lifetime risk of CRC; AOO in 30 s Increased risk gastric, GI, pancreatic CA ~50% of cases have mutations in either the MADH4 or BMPR1A genes

38 Inherited Polyposes Juvenile polyposis Defined as the presence of 5 or more juvenile polyps within the colon Usually diagnosed within the first decade of life: typically presents with bloody stools May present with rectal prolapse or intussusception Genetically heterogenous Three fold increase in risk of colorectal cancer: screen with colonoscopy every two years

39 Inherited Polyposes Cowden s disease Hamartomatous polyps throughout the GI tract; most common in the colon and stomach Mucocutaneous lesions include hyperkeratotic papillomas of lips, tongue and nares 30% incidence of breast Ca in females; also risk of thyroid tumors Lesion on chromosome 10q tumor suppressor gene PTEN encoding a dual specificity phosphatase

42 PRINCIPAL INVESTIGATOR: Roberta A Pagon, MD FUNDED BY National Institutes of Health Contract No. N01-LM-3503 SPONSORING INSTITUTION University of Washington Seattle, WA

44 Sequencing Mutation Clinical of Protein confirmation Prenatal of entire coding scanning region mutations truncation diagnosis identified in a research testing lab

Classification of polyposis syndromes two major groups. Adenomatous polyposis syndromes. Hamartomatous polyposis syndromes

Hereditary polyposis syndromes Classification of polyposis syndromes two major groups adenomatous and non-adenomatous polyposis syndromes Adenomatous polyposis syndromes Familial adenomatous polyposis(fap)