Colon polyps and CRC - Exam 3

colon polyps

precancerous often benign

sporadic or inherited as familial polyposis syndrome

often adenomatous or serrated

adenomatous polyps

pedunculated and raised

MC causes cancer

serrated polyps

sessile, flat, hyperplastic

harder to spot on a colonoscopy since they blend in with the tissue around it

95% of adenocarcinoma in the colon come from

adenomatous or sessile serrated polyps

70% of cancer causing polyps are

adenomas

how many years does it take for a colon polyp to become malignant

10 years

pathophysiology of colon polyps

activation of oncogenes and loss of tumor suppressor genes

genetic change in adenomatous polyps

inactivation of APC gene (a tumor suppressor gene)

genetic change in serrated polyps

Kras mutation and BRAF oncogene

when these are turned on tumors grow

Adenomas

common: 30% of men and 20% of women

small under 5mm with low malignancy risk

advanced if over 1cm

adenomas risk of malignancy

tubular < tubulovillous < villous (highest risk of malignancy)

colon polyps with low cancer risk

diminutive - 5mm or less

small - 6-9mm

colon polyps with higher risk of cancer

large - 1cm or more

serrated because they are harder to find

colon polyp ssx

generally asx

unexplained iron deficiency anemia

melena or hematochezia

polyp/CRC stool based screening

-FOBT - bedside test for blood in stool; least sensitive of all

-FIT - lab send out; more sensitive than FOBT

-Cologuard - send out; best test out of fecal options over 92% sensitive

polyp/CRC direct visualization screening

-CT colonography - dead option

-video capsule - last option only if gold standard is refused

-colonoscopy

Gold standard for CRC screening

colonoscopy - it is diagnostic and therapeutic

when is colonoscopy indicated

-positive FOBT, FIT, fecal DNA

-meet screening guideline

-positive CT or flex sigmoid

video capsule

over 85% sensitive and specific for adenomas over 6mm

drops to 30% for serrated polyps

last resort for those who refuse colonoscopy

colon polyp treatment

colonoscopy with polypectomy

surgical excision if too large - may need multiple rounds of colonoscopy with piecemeal excision if very large

10 year colon polyp surveillance

normal colonoscopy or less than 20 hyperplastic polyps less than 10 mm in distal colon

7-10 year colon polyp surveillance

1-2 adenomas less than 10 mm

5-10 year colon polyp surveillance

1-2 sessile serrated polyps less than 10 mm

3-5 year colon polyp surveillance

3-4 adenomas or sessile serrated polyps less than 10 mm

3 year colon polyp surveillance

5-10 adenomas or sessile polyps less than 10 mm

1 or more adenomas/serrated polyps 10 mm or larger

adenoma containing villous features or high-grade dysplasia

sessile serrated polyp with dysplasia

1 year colon polyp surveillance

more than 10 adenomas

consider screening for FAP

family history of CRC in more than 1 family member

personal or family hx of CRC in someone under 50

personal or family hx of multiple polyps

personal or family hx of multiple extracolonic malignancies

Familial adenomatous polyposis (FAP)

rare, inherited cancer predisposition

hundreds-thousands of precancerous colorectal polyps

extracolonic manifestations

autosomal dominant APC mutation; recessive MUTYH mutation

FAP presentation

polyps by the age of 15; cancer by 40

extraintestinal manifestations - desmoid tumor, osteoma

adenomas in the gastric antrum

FAP Dx

FDR with FAP

multiple adenomas on endoscopy

multigene panel of hereditary cancer genes of APC and MUTYH

FAP Rx

complete proctocolectomy with ileoanal anastomosis or colectomy with ileorectal anastomosis BY AGE 20

colonoscopy q 1-2 years

EGD q 1-3 years

Hamartomatous Polyposis Syndromes

combination of normal and hyperplastic tissue

Peutz-Jeghers syndrome

Familial juvenile polyposis

PTEN (Cowden disease)

Peutz-Jeghers syndrome

young presentation with 1000s of polyps

mets to the breast and testes

familial juvenile polyposis

same presentation as FAP just younger; diagnosed by the age of 5

PTEN

FAP presentation

mets to thyroid, breasts, urogenital tracts

lynch syndrome

inherited nonpolyposis colon cancer

DNA microsatellite instability and inactivation of tumor suppressor genes

early onset CRC that goes everywhere in the body, all different kinds of cancer

what is used to diagnosis lynch syndrome

PRIM 5 Scale or 3-question screen

-CRC or polyps before the age of 50?

-3 or more relatives with CRC ?

-FDR with CRC or another lynch syndrome related cancer before 50?

lynch syndrome management

genetic testing for first degree family members

colonoscopy q 1-2 years beginning at 25 yo or 5 years younger than affected family member

extraintestinal cancer screening

if CRC - subtotal colectomy with anastomosis and annual rectal stump surveillance

CRC

2nd leading cause of cancer death in the US

equal incidence in men and women

develops 4-6 years later in women - estrogen protective factor

CRC risk factors

age over 50, FHx, IBD, genetics, previous radiation

what effect does smoking, alcohol, DM, obesity, physical inactivity on CRC risk

none

aspirin and CRC risk

can reduce the risk of CRC but increases the risk of GI bleeding so significantly - so it is not recommended

CRC ssx

asx for years

melena - right sided blood loss

hematochezia, colicky pain, pencil thin stool - left sided blood loss

tenesmus, urgency, recurrent hematochezia - rectal

fatigue, weakness, anemia,

MCC of apple core sign on UGI

annular carcinoma of the colon

CRC labs

CBC - anemia

elevated LFTs, ALP raise - liver met

CEA - in all with proven CRC and used to measure therapy response; over 5 indicates poor prognosis

where does CRC send mets in men

prostate first and then liver

where does CRC send mets in women

liver

when is CEA not indicated for use of treatment response

if they are not CEA + before intervention

when should a workup be ordered to explain neoplasm

over 40 with:

change in bowel habits

hematochezia

unexplained iron deficiency

occult blood in stool

CRC treatment

surgical resection

stage 2, 3, 4 > oncology

colonoscopy 1 year after surgical resection; no polyps then move to q3-5 years

CRC screening recommendations

USPSTF and ACS for average risk individuals

-annual FOBT or

annual FIT or

flex sig every 5 years or

colonoscopy q10 years or

CT colonography q5 year

CRC screening with FDR

single FDR with CRC at 60+ > colonoscopy at 40 and then q10 if normal

single FDR with CRC before 60 or 2 FDR > colonoscopy at 40 or 10 years younger than FDR and then q5 yr

which section of the colon bears the highest prevalence of CRC

rectosigmoid