The Large Intestine - Colonic and Rectal Polyps and Neoplasms Flashcards
What is Bowel Cancer?
Cancer of the Colon/Rectum - Small Bowel and Anal Cancers are less common.
Risk Factors of Colorectal Cancer (8).
- Family History.
- FAP.
- HNPCC - Lynch Syndrome.
- IBD.
- Increased Age.
- Diet (High in Red/Processed Meat and Low Fibre).
- Smoking.
- Alcohol.
What is FAP?
Familial Adenomatous Polyposis - Autosomal Dominant condition where there is malfunctioning of the tumour suppressor genes - Adenomatous Polyposis Coli (APC) in Chromosome 5.
What is the consequence of FAP?
Adenomas (Polyps) develop along large intestine - potential to become cancerous (usually before 40) (and increased risk of duodenal tumours).
Prophylaxis of FAP.
Panproctocolectomy (removal of entire large intestine) to prevent development of colorectal cancer with an ileo-anal pouch.
What is HNPCC - Lynch Syndrome?
Hereditary Nonpolyposis Colorectal Cancer - Autosomal Dominant condition resulting from mutation in DNA Mismatch Repair Genes.
- MSH2 (60%) and MLH1 (30%).
What is the consequence of HNPCC - Lynch Syndrome?
Higher risk of a variety of cancers, especially colorectal cancers (and endometrial cancer).
What is the difference between HNPCC - Lynch Syndrome and FAP?
HNPCC does not cause adenomas - tumours develop in isolation.
Red Flags of Colorectal Cancer (6).
- Change in Bowel Habit (More Loose and Frequent Stools).
- Unexplained Weight Loss.
- Rectal Bleeding.
- Unexplained Abdominal Pain.
- Iron Deficiency Anaemia (Microcytic + Low Ferritin).
- Abdominal/Rectal Mass on Exam.
Criteria for 2 Week Wait Referral (4).
- Over 40 + Abdominal Pain + Unexplained Weight Loss.
- Over 50 + Unexplained Rectal Bleeding.
- Over 60 + Change in Bowel Habit or Iron Deficiency Anaemia.
- Unexplained Iron-Deficiency Anaemia (?Microscopic Bleeding in Bowel Cancer) : Colonoscopy and Gastroscopy.
Screening of Bowel Cancer (5).
- FIT - Faecal Immunochemical Test : Amount of Haemoglobin in Stool.
- Replaced FOB Test (Faecal Occult Blood) which detected blood but with false positives e.g. from red meats and only 1 sample (compared to 2-3).
- Useful in patients who do not meet criteria for a 2 week wait.
- Age : 60-74 every 2 years or Risk Factors like FAP, HNPCC, IBD.
- If Positive - Colonoscopy.
Investigations of Colorectal Cancer (5).
- Colonoscopy - Gold-Standard (Endoscopy of Entire Large Bowel with biopsy or tattooing).
- Sigmoidoscopy (Endoscopy of Rectum + Sigmoid) : Only Rectal Bleeding.
- CT Colonography (CT Scan with Bowel Prep and Contrast to visualise the colon) : alternative to Colonoscopy but no biopsy/less detailed.
- Staging CT : CT TAP.
- CEA (Carcinoembryonic Antigen) Tumour Marker Blood Test - predict relapse (not screening).
Staging Systems of Colorectal Cancer (2).
- Dukes’ (OLD) - A (Confined to Mucosa) : D (Metastatic Disease).
- TNM System.
Management of Colorectal Cancer (5).
- MDT Meeting.
- Surgical Resection (Curative/Palliative).
- Chemotherapy.
- Radiotherapy.
- Palliative Care (Stent, Bypass, Diversion Stoma).
Surgery in Colorectal Cancer (4).
- Identify tumour - tattoo during endoscopy.
- Remove the section of the bowel containing the tumour.
- Create an end-to-end anastomosis (sew remaining ends back together).
- OR Create a stoma (open section of bowel onto skin).
Types of Surgical Operations (6).
- Right Hemicolectomy.
- Left Hemicolectomy.
- High Anterior Resection.
- Low Anterior Resection.
- Abdominoperineal Resection.
- Hartmann’s Procedure.
What is a Right Hemicolectomy?
Removal of the Caecum, Ascending and Proximal Transverse Colon.
Anastomosis : Ileo-colic.
What is a Left Hemicolectomy?
Removal of the Distal Transverse and Descending Colon.
Anastomosis : Colo-Colic.
What is a High Anterior Resection?
Removal of the sigmoid colon - also known as sigmoid colectomy.
Anastomosis : Colorectal.
What is a Low Anterior Resection?
Removal of the sigmoid colon and upper rectum but sparing the lower rectum and anus.
Anastomosis : Colorectal.
What is an Abdominoperineal Resection?
Removal of the rectum and anus (plus or minor the sigmoid colon) + suturing over anus, leaving the patient with a permanent colostomy.
This is required if there is involvement of the sphincter complex.
What is Hartmann’s Procedure?
Emergency procedural removal of the rectosigmoid colon and creation of a colostomy and the rectal stump is sutured closed.
Common Indications of Hartmann’s Procedure (2).
- Acute Obstruction by a Tumour.
- Significant Diverticular Disease.
Complications of Colorectal Surgery (3).
- Post-Operative Ileus.
- Intra-Abdominal Adhesions.
- Incisional Hernias.
What is Low Resection Syndrome? (3)
- Urgency and Frequency of Bowel Movements.
- Faecal Incontinence.
- Difficulty Controlling Flatulence.
*** after resection of bowel from the rectum, with a colorectal anastomosis.
Emergency Presentation of Colorectal Cancer.
Obstruction - if tumour blocks the passage through the bowel.
Follow-Up with Colorectal Surgery.
After curative surgery : follow-up for 3 years with CT TAP and serum CEA.
Sites of Colorectal Cancer (5).
- 40% - Rectal.
- 30% - Sigmoid.
- 15% - Ascending Colon/Caecum.
- 10% - Transverse Colon.
- 5% - Descending Colon.
When is an end colostomy preferred?
Where the bowel has perforated and the anastomosis is colon-colon.
Genetic Types of Colorectal Cancer (4).
- Sporadic (95%) - series of genetic mutations : Activation of Oncogenes + Inactivation of Tumour Suppressor Genes.
- HNPCC (5%).
- FAP (<1%).
- Serrated Pathway (30%) - Activation of BRAF Oncogene and Silencing of MMR Genes.
What criteria are used to help diagnose HNPCC?
Amsterdam :
1. At least 3 family members with colon cancer.
2. Cases span at least 2 generation.
3. At least 1 case is diagnosed before 50.
What is Gardner’s Syndrome?
Variant of FAP featuring osetomas of skull and mandible, retinal pigmentation, thyroid carcinoma and epidermoid cysts on the skin.
What is a colorectal adenoma?
DYSPLASTIC (Pre-Malignant) Polyp derived from the epithelial cells lining the mucosa - a mass that projects from a mucosal surface.
Descriptions of a polyp (4).
- Pedunculated - attached to mucosa by a stalk.
- Sessile - attached to mucosa by a broad base.
- Tubular - composed of tubular structures.
- Villous - composed of finger-like structures.
What features are associated with a malignant progression of the polyp? (4)
- Increasing Size.
- High Grade of Dysplasia.
- Histology - Villous > Tubular.
- Invasion of Submucosa - Metastatic Potential.
What is an adenoma?
Definition : benign tumour of glandular epithelium, with no potential to become cancerous.
GI : premalignant lesions.
