GI cancers Flashcards
What are the different types of GI cancers and how do you classify them?
- epithelial cells. Eg. Squamous cell –> squamous cell carcinoma. Glandular epithelium –> adenocarcinoma
- neuroendocrine cells: enteroendocrine cells –> neuroendocrine tumours. Intestinal cells of cajal —> gastrointestinal stromal tumours GISTs
- connective tissue: smooth muscle –> leiomyoma/leiomyosarcoma. Adipose tissue –> liposarcoma
What are the most common type of GI cancer?
adenocarcinoma
In oesophageal cancer, what is a squamous cell carcinoma and what is it related to?
- SCC arises from normal oesophageal squamous epithelium (upper 2/3rds of oesophagus).
- Related to acetaldehyde pathway (alcohol metabolised by alcohol dehydrogensase to form acetaldehyde).
- More in less developed world
In oesophageal cancer what is an adenocarcinoma and what is it related to?
- Arises from metaplastic columnar epithelium in lower 1/3rd of oesophagus.
- Related to acid reflux & more common In developed world
What is the progression of gastric reflux to cancer? What interventions do you do at each stage?
Oesophagitis (GORD) –> barret’s oesophagus (metaplasia) –> dysplasia (low or high grade) –> adenocarcinoma.
- Metaplasia: endoscopy every 2-3 years.
- Low grade dysplasia: endoscopy every 6 months.
- High grade dysplasia intervene to prevent it becoming adenocarcinoma
What are the demographics of oesophageal cancer?
Affects elderly. More men than women
What is survival in oesophageal cancer like and why?
- Usually present late with dysphagia & weight loss by then too advanced.
- High morbidity & complex surgery with poor 5-year survival.
- Palliation hard (rely on oesophageal stents)
How do you diagnose and stage oesogphageal cancer?
- In endoscopy if anything abnormal biopsy it.
- For staging: CT scan, laparoscopy for metastases, if highly suspicious but submucosal do EUS, PET scan to pick up metastases (occult)
How do you treat oesophageal cancer?
- squamous cell carcinoma: radiotherapy
- adenocarcinoma: neo-adjuvant chemotherapy, re-staging, radical therapy (surgery).
- palliative (chemo, DXT radiotherapy, stent)
What is oesophagectomy? Risks?
- Ivor Lewis approach: remove some of oesophagus and join it to stomach.
- High morbidity & mortality risks
What are the demographics of colorectal cancer?
Most common GI cancer in west. Little more in men. Usually >50 years old
What are the forms of colorectal cancer?
- sporadic: no Fx, older, isolated lesion.
- familial: Fx, higher risk if case is under 50 & relative is 1st degree
- hereditary syndrome: Fx, younger age onset, gene defects eg. Familial adenomatous polyposis FAP or hereditary non-polyposis colorectal cancer HNPCC or lynch syndrome
How does an adenocarcinoma (colorectal) happen/progress? What can be done to prevent?
- Normal epithelium gets mutated, hyperproliferative epithelium with COX2 expression leads to small adenoma –> large adenoma –> colon carcinoma.
- If polyp seen in colonoscopy remove them.
- Aspirin may help progression of polyps to cancer
What are risk factors of colorectal cancer?
- Past history of colorectal cancer, adenoma, ulcerative colitis, radiotherapy.
- Family history 1st degree <55 years or relatives with genetic predisposition (FAP, HNPCC, peutz-jeghers syndrome), diet/environment, carcinogenic foods, smoking, obesity, socioeconomic status
What does clinical presentation of colorectal cancer depend on?
Location of cancer.
- 2/3rd in descending colon/rectum.
- 1/2 in sigmoid colon/rectum (within reach of sigmoidoscopy)
What is clinical presentation of colorectal cancer?
- caecal & R sided cancer: iron deficiency, change bowel habits (diarrhoea), distal ileum obstruction later, palpable mass later. More likely to bleed
- L-sided & sigmoid carcinoma: PR bleeding, mucus, thin stool
- rectal carcinomas: PR bleeding, mucus, tenesmus (feeling want to open bowels but not - because of sensation of tumour there), anal/perineal/sacral pain (late). 4. bowel obstruction (late)
- local invasion (late - bladder, female genital tract symptoms)
- metastases (late) - liver causing hepatic pain & jaundice, lung causing cough, regional lymph nodes, peritoneum (sister mary joseph nodule - metastasis in umbilical)
What are examinations for colorectal cancer? For primary cancer & secondary cancer signs?
- primary cancer: abdominal mass, digital rectal examination DRE most <12cm dentate & by reach of finger, rigid sigmoidoscopy, abdominal tenderness & distension point to large bowel obstruction
- metastasis/complications -> hepatomegaly, monophonic wheeze, bone pain
What are investigations used for colorectal cancer?
- Faecal occult blood FIT test: detect small amounts of blood in stool
- Guaiac test (haemoccult - based on pseudoperoxidase activity of haematin - avoid red meat, melons, vitamin C, NSAIDS 3 days before test)
- FBC - anaemia, low ferritin
- tumour markers: CEA useful in monitoring (if high initially and goes down after treatment)
- colonoscopy - visualises lesions <5mm, small polyps removed, usually sedation
- CT colonoscopy/colonography: no sedation, better tolerated. Lesions >5mm, if lesions need colonoscopy for diagnosis.
- MRI pelvis (rectal cancer –> depth of invasion, mesorectal lymph nodes, no bowel prep needed, helps choose between pre-op chemo or straight to surgery)
- CT chest/abdo/pelvis - staging to exclude metastases before treatment
How is colorectal cancer managed? what do you do if right/left obstructing cancer?
- Surgery. Resection of bowel depends on blood supply. remove part of bowel + join remaining to the others
1. right & transverse colon - resection & primary anastamosis if obstructing (usually don’t)
2. left sided obstruction do hartmann’s procedure (proximal end colostomy LIF +/- reversal in 6 months. Or primary anastomosis but 10% leak, defunctioning ileostomy. Can do palliative stent.
What is the most common type of pancreatic cancer and when do they usually present?
Pancreatic ductal adenocarcinoma PDA.
-Most present late because causes symptoms late (by then invading or metastases)
What is the epidemiology of pancreatic cancer?
Higher in wester countries, rare before 45, 4th commonest, 2nd commonest cause of cancer death
What are risk factors for pancreatic cancer?
Chronic pancreatitis, type II diabetes, cholelithiasis, previous gastric surgery, pernicious anaemia, smoking, family history, occupation (insecticides, aluminium, nickel, acrylamide)
What genes are involved in hereditary pancreatitis and what do they cause risk of?
PRSS1, SPINK1, CGTR.
Cause 40% lifetime risk of PDA
What is the pathogenesis of pancreatic cancer?
PanIN progression model.
Normal epithelium –> PanIN1 –> PanIN2 –> PanIN3 –> stage before cancer.
-Each stage associated with different mutation, often takes years to progress but when become cancer metastasize quickly before causing local problems
