9 - Colorectal Flashcards
What is the epidemiology of colorectal cancer?
- Fourth most common cancer
- Third most common cancer in both men and women, whilst it is fourth most common overall
- Peak incidence 85-89
What are some risk factors for colorectal cancer?
THINK ABOUT MODIFIABLE AND NON-MODIFIABLE
- Older age
- Family history
- Hereditary syndromes
- Inflammatory bowel disease
- Caucasian
- Radiotherapy
- Obesity
- Diabetes mellitus
- Smoking
- Red meats and processed foods
What are the locations of cancer in colorectal cancer?
Most common in rectum then sigmoid
More prevalence in left side of colon
What dietary source is protective against colon cancer?
Fibre
What are the hereditary syndromes and the genetic mutations they have that predispose to colorectal cancer?
Hereditary nonpolyposis colorectal cancer (Lynch Syndrome) (most common)
- Autosomal dominant
- Common mutations include MLH1, MSH2, MSH6 and PMS2
- DNA mismatch repair genes
- can also increase womans risk of endometrial cancer
Familial adenomatous polyposis
- Autosomal dominant
- Mutations to the adenomatous polyposis coli (APC) gene - tumour suppressor gene
- Development of numerous adenomatous polyps in the colon and rectum, some of which undergo malignant change
What other malignancies are those with HNPCC (lynch syndrome) at risk of?
- Endometrial
- Ovarian
- Small bowel
- Gastric
- Gallbladder
- Liver
- Brain
- Renal tract
How many people with FAP get colorectal cancer and how is this risk managed?
- 90% before the age of 45 if not treated
- Screening commenced at the age of 12-14 with an annual colonoscopy
- Prophylactic total colectomy with ileo-anal pouch formation may be offered at an appropriate time following discussion with patient
What other malignancies are those with FAP at risk of?
- Duodenal tumours
- Gardner’s syndrome: osteomas of the skull and mandible, retinal pigmentation, thyroid carcinoma, epidermoid cysts on the skin
What are some other syndromes apart from HNPCC and FAP that predispose to bowel cancer?
- Juvenile polyposis
- Peutz-Jeghers syndrome
What is the Amsterdam criteria?
Way of diagnosing HNPCC
What is the pathophysiology of colorectal cancer?
Adenocarcinomas (70% sporadic, inherited 5-10%, familial 20%)
Adenoma-Carcinoma sequence
- Mutations are accumulated over a number of years leading normal epithelium to develop adenomas, which become progressively more dysplastic and eventually develop into a carcinoma
- Early mutations to tumour suppressor adenomatous polyposis coli (APC) which leads to the hyperproliferative epithelium
- Then KRAS, a proto-oncogene, that becomes an oncogene following mutation
- Further mutations to p53 (tumour suppressor) as well as SMAD4 and others leads to the development of a carcinoma from an adenoma
20-25% of colorectal cancers are metastatic on presentation. Where do they tend to metastasise to?
- Lung (especially rectal as drains into IVC)
- Liver (as drain into portal system - MOST COMMON)
- Peritoneum
- Bone
How may colorectal cancer present? (symptoms in history)
Change in bowel habit, Anaemia and Weight loss are most common
- Asymptomatic and found on screening
- Endoscopy for unexplained iron deficiency anaemia
- Change in bowel habit e.g constipation or diarrhoea
- Weight loss
- Bowel obstruction in ⅓ of presentations
- Malaise
- Tenesmus
- PR bleeding
- Abdominal pain
What signs may you see on examination if somebody has colorectal cancer?
- Pallor
- Abdominal mass
- Abnormal PR
How may colorectal cancer present if it has already metastasised?
- Hepatomegaly
- Jaundice
- Abdominal pain
- Lymphadenopathy
How does right vs left sided colon cancer present differently?
Right: usually iron deficiency anaemia
Left: usually develops circumferentially so apple core sign and a change in bowel habit and eventual bowel obstruction
Who is offered screening for bowel cancer on the NHS and what test do they use to screen?
Every 2 years to all men and women aged 60 to 74 years (changing to 56). Over 74 can request screeningevery 2 years
Faecal Immunochemical Test (FIT): faecal occult blood test that uses antibodies to determine how much human Hb/blood in a stool sample. Doesn’t pick up animal blood from diet
If patients have a positive result from FIT test what are they then sent for?
Colonoscopy
Who else is eligible for a FIT test apart from 60-74 year olds?
Those who have symptoms but do not fit the criteria for a 2 week wait referral
How are those with FAP, HNPCC and IBD screened for colorectal cancer?
Annual colonoscopy
What is the referral criteria for a 2 week wait for colorectal cancer?
- patients >= 40 years with unexplained weight loss AND abdominal pain
- patients >= 50 years with unexplained rectal bleeding
- patients >= 60 years with iron deficiency anaemia OR change in bowel habit
- tests show occult blood in their faeces
What are red flags for colon cancer?
- Change in bowel habit (usually to more loose and frequent stools)
- Unexplained weight loss
- Rectal bleeding
- Unexplained abdominal pain
- Iron deficiency anaemia (microcytic anaemia with low ferritin)
- Abdominal or rectal mass on examination
What investigations are done as part of the two week wait for colorectal cancer?
- Colonoscopy: Gold standard. Usually under sedation but a lot cannot tolerate. Can biopsy suspicious lesions
- Flexible Sigmoidoscopy: if cannot tolerate above
- CT pneumocolon: if colonoscopy not suitable, use bowel prep and contrast
- CT TAP: to look for metastases for staging - thorax, abdo, pelvis
What are the complications of a colonoscopy?
- Patients cannot tolerate just under sedation so may not view full colon
- Risk of perforation especially in diverticular disease
- Must be able to comply with Moviprep bowel preparation
Apart from imaging what are some other investigations done in the workup for colon cancer?
Bloods
- FBC
- Serum iron, transferrin saturation, TIBC
- Renal function
- LFT
- Clotting screen
Carcinoembryonic antigen (CEA)
- Tumour marker that can help monitor treatment and recurrence
MRI Rectum
- If tumour sits below peritoneal reflection
How is colon cancer staged?
Used to be Duke’s criteria, now TNM
What is Duke’s classification?
- Dukes A – confined to mucosa and part of the muscle of the bowel wall
- Dukes B – extending through the muscle of the bowel wall
- Dukes C – lymph node involvement
- Dukes D – metastatic disease
What management is available for colon cancer and what does it depend on?
- Surgical resection
- Chemotherapy
- Radiotherapy
- Palliative care
Most treatment is surgery whether curative or palliative e.g stents
How is colorectal cancer treated with surgery? (including different procedures)
-
Stage I-III disease: surgical resection ± post-operative chemotherapy.
The type of surgery depends on the tumour site - Patients with stage III disease (lymph node involvement): post-operative adjuvant chemotherapy
- For stage IV disease (metastases): treatment as above, but pre-operative chemotherapy
How do you decide whether to create a stoma or anastomosis after surgical resection for colon cancer?
For an anastomosis to heal need: adequate blood supply (the close contact or joining of the mucosal layers of tissues), mucosal apposition and no tissue tension
Surrounding sepsis, unstable patients and inexperienced surgeons may compromise these key principles and in such circumstances it may be safer to construct an end stoma rather than attempting an anastomosis
Can always reverse stoma later
How is rectal cancer treated surgically?
- Anterior resection if the proximal 2/3 of the rectum
- Abdomino-perineal (AP) resection if distal 1/3 of the rectum
- TME: clearance of fat and lymph nodes
Early Rectal Cancer
- Transanal excision
- Endoscopic submucosal dissection
- Total mesorectal excision (TME)
Advanced Rectal Cancer
- Total mesorectal excision (TME) with anterior resection or AP resection
- Pre-operative radiotherapy or chemoradiotherapy
What emergency surgical procedure is done for a colorectal cancer causing bowel obstruction?
Hartmann’s Procedure
Rectosigmoidcolectomy with end colostomy and closure of rectal stump
What are the complications of surgery for bowel cancer?
- Bleeding, infection and pain
- Damage to nerves, bladder, ureter or bowel
- Post-op ileus
- Anaesthetic risks
- Laparoscopic surgery converted during the operation to open surgery
- Leakage or failure of the anastomosis
- Requirement for a stoma
- Failure to remove the tumour
- Change in bowel habit
- Sexual dysfunction
- Venous thromboembolism (DVT and PE)
- Incisional hernias
- Intra-abdominal adhesions
What stoma is made in rectal cancer surgery?
Loop ileostomy as high risk of anastomotic leak
How can you estimate the risk of death with colon cancer surgery?
SORT score
What is low anterior resection syndrome?
May occur after resection of a portion of bowel from the rectum, with anastomosis between the colon and rectum
- Urgency and frequency of bowel movements
- Faecal incontinence
- Difficulty controlling flatulence
What is some adjuvant and neo-adjuvant treatment for colon cancer and when is it given?
Neoadjuvant therapy
- Rectal cancer cT1-T2, cN1-N2, M0, or cT3-T4, any cN, M0 should be offered neoadjuvant radiotherapy or chemoradiotherapy
- Colonic cancer with cT4 disease. Consider the use of chemotherapy
Adjuvant therapy
- FOLFOX (FOLinic acid, Fluorouracil and OXaliplatin)
- CAPOX (CAPecitabine and OXaliplatin)
How are those with metastatic colon disease managed?
Metastasectomy or other local therapies to target metastatic deposits as well as systemic anti-cancer therapy
May surgically resect tumour
Liver metastasis
- Simultaneously: Removed at the same time as the primary tumour
- Sequentially: Removed in a separate procedure either before or after the primary tumour.
For those that are not resectable, local ablative techniques and chemotherapy may be considered
Lung metastasis
Metastasectomy, ablation and stereotactic body radiation therapy.
Peritoneal metastasis
Systemic anti-cancer therapy.
At specialist centres cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) may be considered
What monoclonal antibodies are offered in metastatic colon cancer?
Cetuximab (anti-EGFR) or Bevacizumab (anti-VEGF) in combination with chemotherapy
How are patients followed up after their curative surgery?
Set period of time (e.g., 3 years):
- Serum carcinoembryonic antigen (CEA)
- CT thorax, abdomen and pelvis
How can colon cancer be prevented?
- Patients should be encouraged to maintain a healthy balanced diet
- Cut down on processed meats
- Smoking cessation
- Healthy weight
- Daily aspirin for at least 2 years in Lynch syndrome
What is the prognosis with colon cancer?
How does Peutz-Jeghers syndrome present?
- Mutation in the STK11 gene
- Autosomal dominant
- In teens with mucocutaneous pigmentaiton and hamartomatous polyps.
Risk of neoplastic transformation of hamartomatous polyps is low, but many polyps are present so patients are at increased risk of developing colorectal cancer. They are managed with regular endoscopic surveillance
What is iron deficiency anaemia until proven otherwise?
Colon caner
What are the long term side effects of bowel cancer treatment?
Don’t forget mental health and sexual issues!
What are some GI side effects of bowel cancer treatment?
- rectal bleeding
- faecal incontinence
- urgency
- diarrhoea
- constipation
- flatulence
- abdominal pain
- painful bowel movements
How can we improve the long term side effects that patients have after bowel cancer treatment?
Refer to community nurse clinic!
What questions can you ask to see if patient is having late GI side effects?
- Are you woken at night to have a bowel movement?
- Do you need to rush to the toilet to have a bowel movement?
- Do you ever have bowel leakage, soiling or a loss of control over your bowels?
- Do you have any bowel symptoms preventing you from living a full life?
