Colorectal Flashcards by Olivia Ray

How do most colorectal cancers arise and what is the most common type?

From polyps to form adenocarcinomas

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What are the layers of the bowel wall, from lumen outwards?

Mucosa - contains connective tissue lamina propria and muscularis mucosa.

Submucosa - connective tissue, glands, vessels, lymph nodes, nerves

Muscularis propria
Subserosa
Serosa

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What are risk factors for colorectal cancer?

Family history
Hereditary syndromes
Inflammatory bowel disease
Ethnicity
Radiotherapy
Obesity
Diabetes mellitus
Smoking
Western diet - low fibre, high fat, red/processed meat

Increased exercise is protective

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What hereditary syndromes increase the risk of CRC?

Hereditary nonpolyposis colorectal cancer/Lynch syndrome - autosomal dominant mutation

FAP - familial adenomatous polyposis - autosomal dominant mutation of APC (tumour suppressor gene)
Development of polyps that could undergo malignant change

Require annual colonoscopy

MYH associated polyposis
Serrated polyposis
Juvenile polyposis
Peutz-Jeghers syndrome

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What is the adenoma-carcinoma sequence?

Mutations accumulate
Normal epithelium develops adenomas which become progressively more dysplastic = carcinoma

APC mutation leads to hyper proliferative epithelium, then KRAS mutation of proto-oncogene - oncogene.
The mutation of p53 and SMAD4 leads to development of carcinoma

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Where does CRC most commonly occur?

Rectum and sigmoid colon

Most commonly affect the left side of the colon

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Where do CRCs commonly spread?

Liver most commonly

Rectal cancers commonly associated with lung mets due to haematogenous spread via inferior rectal vein and IVC

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What are the clinical features of CRC?

Change in bowel habit
Weight loss, malaise
Tenesmus, PR bleeding
Abdominal pain
Pallor
Abnormal PR exam, mass

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How does the presentation of right sided to left sided colon cancer differ?

RS: weight loss, weakness, rarely obstruction, iron deficiency anaemia, late

LS: constipation, abdo pain, alternating bowels, rectal bleeding, bright red PR bleeding, large bowel obstruction

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How does a rectal cancer present?

Obstruction, tenesmus, bleeding
Bright red PR bleeding
Palpable mass on DRE

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How can mets present with liver involvement?

Hepatomegaly
Jaundice
Abdo pain
Lymphadenopathy

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What appearance can left sided lesions present as?

Have a tendency to grow circumferentially, creating an apple core appearance
So leads to narrowing of the lumen - obstruction

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What screening is available?

FIT test - Faecal Immunochemical test for presence of blood in the stool
56-74 home test kit every 2 years

Those with abnormal results will be invited for colonoscopy

One-off flexible sigmoidoscopy paused since COVID19 - aged 55

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Who should be referred for two week wait?

Most can be sent straight to test for colonoscopy unless contraindication/complication

Aged 40 + with unexplained weight loss and abdo pain
Aged 50 + and unexplained rectal bleeding
Aged 60 + with iron deficiency anaemia, change in bowel habits
Test shows occult blood
Consider patients with rectal or abdominal mass

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What are the investigations for suspected CRC?

Colonoscopy is the gold standard investigation

CT pneumocolon - but cannot take biopsy or remove polyps

CT abdomen pelvis with or without contrast

Bloods - FBC, iron, transferrin, TIBC, renal function, LFT, clotting

Tumour markers - CEA

MRI liver, rectum
Endoanal USS
PET/CT for staging

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When should neoadjuvant therapy be offered?

Rectal cancer T1-T2, N1-N2, M0

Colonic cancer with cT4 consider use of chemo

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What are some examples of adjuvant therapy?

FOLFOX - Folinic acid, Fluorouracil, Oxaliplatin

CAPOX - Capecitabine and Oxaliplatin

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What is the Duke staging?

A - tumour confined to mucosa
B - growth into muscularis propria +- serosa
C - spread to lymph nodes
D - distant mets; liver, lung, bones

What signs would suggest advanced colorectal cancer?

Hepatomegaly

Jaundice

When is a right hemicolectomy performed? What is done during the procedure?

Any ascending colon tumours

Part or all of ascending colon and cecum removed. Colon anastomosed to small intestine (ileo-colic)

When is a left hemicolectomy performed? What is done during the procedure?

Any descending colon tumours

Part or all of descending colon removed. Transverse colon anastomosed to rectum (colo-colic)

When is a sigmoid colectomy performed? What is done during the procedure?

Tumours affecting the sigmoid colon

Part/all of sigmoid colon removed. Descending colon connected to rectum (colo-rectal)

When is an anterior resection performed? What is done during the procedure?

High anterior resection: sigmoid tumours
Anterior resection: rectal tumours

sigmoid colon and portion of rectum removed. Colorectal anastomosis formed
+TME (removal of mesorectal fat and lymph)

When is an abdo-perineal resection performed? What is done during the procedure?

Lower rectal tumours and any tumour involving the sphincter

removes the anus, rectum, and sigmoid colon. No anastomosis

Where does a HNPCC colon cancer normally affect? | What other cancers is HNPCC associated with?

Proximal colon Endometrial

What are some complications of colorectal cancer surgical management?

Anastomotic leak, adhesions, hernia Stoma complications: - parastomal hernia, ischaemia/necrosis, obstruction, skin irritation, prolapse, retraction leading to a poor bag seal

What is Hartmanns' procedure?

Resection of sigmoid colon, closure of the anorectal stump and formation of end colostomy

What are the advantages and disadvantages of parenteral nutrition?

little patient effort sepsis catheter obstruction thrombosis refeeding syndrome

What are the advantages and disadvantages of enteral nutrition?

low cost maintains gut few infection risks aspiration risk tube displacement gastric distention risk of malnutrition

What are the most common tumours that cause bony mets?

Prostate, breast, lung

Where are the most common sites for bony mets?

Spine, pelvis, ribs, skull, long bones

What are hamartomas?

Hamartomatous polyps Non cancerous tumours made of overgrowth of normal cells Usually asymptomatic Not associated with malignant transformation or increased risk of colorectal cancer

What are some of the side effects of bowel resection?

``` Pain, bleeding Thrombosis Paralytic ileus Abdominal adhesions Anastomotic leak Infection Sexual problems - erectile dysfunction, retrograde ejaculation, dry orgasm Bladder problems - urinary incontinence, urgency, frequency ```

What are some of the side effects of chemo?

``` Bone marrow suppression Diarrhoea Skin changes - rash, photosensitivity Hair loss Sore mouth and throat - stomatitis, oral mucositis Nausea and vomiting Loss of appetite Pain at the injection site Peripheral neuropathy Liver damage Allergic reactions ```

What are some agents that can be used in targeted therapy?

Cetuximab Panitumumab Bevacizumab

What are treatment options to those with early rectal cancer?

Transanal excisions Endoscopic submucosal dissection Total mesorectal excision Total mesorectal excision with anterior or AP resection in more advanced rectal cancers

What should be performed in a follow up?

Physical examination Attention to Virchow's node left supraclavicular node CEA for elevation Colonoscopy within 12 months of completing primary treatment, then every 3 years, then every 5 years Those with rectal cancer undergo flexible sigmoidoscopy CT chest and abdomen, CXR rectal cancers check for mets

What are some specific side effects in chemotherapy?

5FU/capcitebine - hand and foot skin breakdown Oxaliplatin - peripheral neuropathy HTN and GI bleeds - Bevacizumab Skin rashes - cetuximab

What are the main signs and symptoms of large bowel obstruction?

``` Absolute constipation Vomiting (late stage) Abdominal distention Loud normal bowel sounds Non tender abdomen Empty rectum ```

How is large bowel obstruction managed?

Conservatively - drip and suck fluid resuscitation and intestinal decompression or stenting endoscopy

How would a competent ileo-caecal valve affect large bowel obstruction?

Fluids and materials can pass in but not out meaning the large bowel distends rapidly and the caecum will rupture causing peritonitis If incompetent, small bowel will also distend so perforation isnt as big a risk

How does small bowel obstruction present?

``` Colicky umbilical pain Vomiting - pain relief Abdominal distention Tinkling bowel sounds Palpable loops of bowel ```

How is small bowel obstruction managed?

Drip and suck - fluid resus and tube for decompression Watch and wait as may need laparotomy

What is a complication of small bowel obstruction?

Strangulated obstruction when blood supply become impaired --> ischaemia and gangrene within 6hrs of onset