Intestinal neoplasia Flashcards
Name the parts of the small intestine
Duodenum
Jejunum
Ileum
Duodenum features and function
- shortest region
- retroperitoneal
- starts at pyloric shincter and is C-shaped tube
- Duodenum means 12 - named because it is as long as the width of 12 fingers
Function: Digestion
Jejunum features and function
- 1m long extends to ileum
- jejunum means “empty” which is how it is found at death
Function: Absorption
Ileum features and function
- 2m long joins large intesting at a smooth muscle sphincter called ileocecal spinter
Primary functions of the small intestine
- further digestion of food, aided by pancreatic enzymes (forproteins) and bile (for fat).
- Lipids, peptides and sugars are all absorbed in the intestine
How long is the small intestine?
3m
Histology of the small intestine
- mucosa
- simple collumnar epithelium
- contains:
- absorptive cells - digest and absorb nutrients
- goblet cells - secrete mucus
- Deep crevices
- intestinal glands or crypts of liberkuhn - secrete intestinal juice
- submucosa (loose connective tissue),
- contains brunner gland - secrete and alkaline mucus that helps neutralise gastric acid in the chyme
- muscularis propria (thick muscle to move food),
- subserosal fat/adventitial fat (depending on location)
Which features of the small intestine Increase the surface area?
Circular folds or plica - folds of mucosa and submucosa, permanent ridges, near porximal portion of duodenum that enhance the surface area
Villi- finger like projections of mucosa, increase the surface area
Microvilli- projecions of apical(free membrane) of the absorptive cells on villi
Which ducts does the smalll intestine receive?
- Pancreatic dunct
- Bile duct
Controlled by the Spincter of oddi
- muscular valve that controls the flow of digestive juices (bile and pancreatic juice) through the ampulla of Vater into the second part of the duodenum.
Name the Parts of the large intestine
Features of the large intestine
- 1.5 m long extends from ileum to anus
- attached to posterior abdominal wall by mesocolon( double layer of periotenum)
Histology of the large intestine
- Mucosa
- simple collumnar epithelium
- absorptive
- goblet cells
- simple collumnar epithelium
- submucosa
- Musculars (CILO)
- Taenia coli - three separate longitudinal ribbons of smooth muscle on the outside of the ascending, transverse, descending and sigmoid colons. -ongtiudinal contraction
- Haustra - small pouches caused by sacculation, which give the colon its segmented appearance- circular contraction
Main function of the large intestine?
- absorption of water and electrolytes,
- Ileo-caecal valve prevents large intestinal contents passing back into small intestine – significant if obstruction nearby
Blood supply of the GI tract
3 main vessels all arising from the abdominal aorta
Epidemiology of Colorectal cancer
- Lifetime risk
- 1 in 16 for men (6%)
- 1 in 20 for women (5%)
- Overall 50% 5-year survival rate
Risk factors for colon cancer
- increasing age
- smoking (2-3 increased risk)
- Diseases:
- previous CRC
- IBD: Crohns/ UC
- Diet- low in fibre, high in red meat, processed meat
- reduced exercise
- increased alcohol intake
Pathogenesis of adenoma-carcinoma sequence
- Normal colon is exposed to DNA damage e.g. from bile acids / slow transit of stool etc.
- Accumulate mutations or may have inherited some mutations:
- APC / DCC – tumour suppressor genes
- Activation of oncogenes e.g. K-ras
- Adenomas – dysplastic but BENIGN neoplasms of glandular origin - NOT yet cancer as contained within mucosa
- Further mutations; basement membrane breached - adenocarcinoma
What are polyps?
Benign overgrowths in mucous membranes
- ricks of malignant change is related to number and size
- sessile polyps tend to develop into cancer and more often than peduculated polyps
Clinical features of benign disease
most andeomatous lesions have to clinical signs and are picked up on screening
Management of benign disease
Endoscopic mucosal resection (EMR) – this is a technique to remove polyps by colonoscopy. Upon discover of one or more polyps, colonoscopy, and subsequent EMR is advisable, whereby all visible lesions should be removed.
The patient should then be given regular and lifelong surveillance (every 3-5 years up to the age of 75) to check for the development of more polyps and / or colorectal cancer.
50% of patients will develop further polyp
Malignant potentials of adenomas
- size
- number
- histological type
Differential of adenomas
- Hyperplastic (metaplastic) polyps
- Hamartomatous polyps – normal tissue, disorganised in structure
- Inflammatory polyps – resulted from overgrowth as part of a healing response
- Submucosal lesions- e.g.lipoma, leiomyoma
Types of colorectal cancer
Familial adenomatous polyposis (FAP)
Hereditary Non-polyposis Colon cancer (HNPCC)
Familial adenomatous polyposis (FAP)
- Due to autosominal dominant APC gene (tumour suppressor gene) or Autosomal recessive MUTYH gene
- ‘Carpet’ of polyps – 1000s!
- Not common
- Linked to retinoblastoma gene so use opthalmoscopy to confirm diagnosis
- Mechanism: Via phosphorylation of beta-catenin, the APC protein which controls activation of a variety of transcription factors within cells.. Affects expression of a variety of genes thatchange proliferation and differentiation of cells
Hereditary Non polyposis Colonic Cancer (HNPCC)
- Lynch syndrome
- The adeno-carcinoma sequence progresses at a v.fast rate in these patients
- Affected genes: MLH-1, MSH-2, MSH-6 and PMS2 genes
- Involved in DNA mismatch repair genes and loss of function leads to more rapid development of abnormal genetics
- Traits:
- Cancer develops at younger age
- Mainly right sided
- More mucinous than average population
- Other cancers more common endometrial, gastric, etc.
Presenting complaint
Two types of presentation
- Elective – the patient may have experienced the symptoms for some time. The symptoms tend to be chronic rather than acute
- Emergency – the patient experiences a sudden-onset of acute symptoms e.g. pain due to a perforation in the bowel
Long standing symptoms
- Change in bowel habit – typically persistent diarrhoea with episodes of constipation
- Anaemia – associated lethargy
- Rectal bleeding – CRC is NOT top differential!!!
- Tenesmus
- Patient may feel a lump (R side e.g. caecal tumour)
- Rarely get pain unless due to abdo distension (only pressure receptors in bowel)
- Weight loss and anorexia
Emergency presentaiton
Signs of bowel obstruction:
- Abdominal distension
- Absolute constipation
- Nausea / Vomiting
Signs of bowel perforation:
- Acute onset constant pain
Remember Apple core- appearance complete constriction
Staging of Colorectal cancer -TMN staging
TMN staging depends on how far through the bowel wall the tumour has invaded
T (tumour)
- within submucosa
- within muscle layer
- through muscle layer
- outwith bowel wall
N (nodes)
0 -no nodes involved
- less than 4 nodes +ve
- more than or equal to 4 nodes +ve
M (metastasis)
- no mets
- distant mets
Duke’s criteria
Distant metasasis
Liver most common
Lungs
Bone (more common in rectal cancer) -leucoerthyroblastic anaemia
Brain
Investigations in colorectal cancer
- Bloods - FBC, (U&Es), LFTs, CEA
- Colonoscopy (or flexible sigmoidoscopy if low risk) + Biopsy (diagnostic differentiation graded 1-3)
- CT colonography- 3D reconstruction which helps to look at corners (stillrequires bowel prep)
- Emergency CT scan (eg in case of perforation cannot empty bowel using bowel prep as this would pump faeces into peritoneum)
What investigation would you do to identify invasion?
CT scan- chest abdo pelvis
MRI scan of rectum if rectal tumour
Liver USS- first site of mets usually
Can do CT PET to look for other mets
Symptoms of malignant disease
Sign of spread
Sister mary joesph nodule: lymph node at the ubillicus that is a sign of spread
Where do the cancers occur?
34% in rectum
24% in sigmoid colon
4% in descending colon
6% in transverse
= most occur in left side
28% right side
Screening test for bowel cancer?
50-74 years olds are offered a feacal occult blood test (FObt); not very specific every 2 years
Faecal immunochemistry test (FIT)
- antibody for the globin part of haemoglobin
- more sensitive; used for spoiled kits or equivocal cases
Treatment for malignant disease
Right hemicolectomy:
The right side of the colon, just past the hepatic flexure, is removed and the ends rejoined - anastomosis
Left hemicolectomy : The left side of the colon (from just before the splenic flexure up to the sigmoid colon) is removed and the ends are anastomised
Sigmoid colectomy: The sigmoid colon is removed and the remained is anastomised
Total colectomy:
•The colon is removed but the anus and rectal stump are left in situ and an end ileostomy is formed
•Ulcerative colitis, Crohn’s and FAP
•More likely to be done in an emergency than a pan proctocolectomy
•Ileo-rectal anastomosis, proctectomy (removal of rectum + anus) or formation of an ileo-anal pouch may be carried out later for selected patients
Surgical management involving the ileum, colon, rectum and anus
Pan proctocolectomy:
•Colon, rectum and anus are removed
•End ileostomy is formed
Crohn’s, ulcerative
Rectum surgical management
Lower anterior resection of rectum:
•The lower portion of the rectum and lower part of the sigmoid colon are excised and the ends anastomised
•A temporary loop colostomy or loop ileostomy is formed in the transverse colon to protect the anastomosis (reversed later on)
Higher anterior resection or rectosigmoid resection:
•The portion of the colon at the rectosigmoid junction is excised and anastomosis formed
•Sometimes a covering loop colostomy or loop ileostomy is required
Abdominoperineal resection of rectum
•The sigmoid colon, rectum and anus are removed
•Have an abdominal and perineal wound
•End colostomy formed
•Performed for rectal cancer
Types of stoma
ileostomy- is an opening of the small intestine(ileum), usually on the right side of the abdomen and it should protrude from the body
two main types:
- End ileostomy- the colon may have been removed; the some acts several times a day and the output is loguid
- Loop ileostomy- may be formed to direct faeces away from a problem area of bowel
Colostomy- is an opening from the large bowel (colon) and may be temprorary or permanent
Two main types:
- End colostomy - formed when part of the colon and/or rectum is removed and the large bowel is not rejoined. Usually on the left side of the abdomen and flush with skin
- loop colostomy- normally to diver faeces awau from a problem area in the bowel
Screening criteria
Minimally invasive, simple, safe and precise test
FOBt - of no harm to patient, not invasive at all
Not very precise hence follow up with colonoscopy
Catches disease at an early stage
Yes – FOBt often picks up CRC when it is still asymptomatic
Early diagnosis is of benefit to prognosis
Yes – may mean spread locally / metastases is avoided
Has a target population
Over 50 years old
Is an important health concern
3rd most common cancer in UK (after breast and lung cancer)
50% mortality at 5 years
Is economically viable – YES!
Deciding which treatment according to duke stage
