Tumors of Colon Flashcards
What is a benign tumor of colon/rectum
What is a malignant tumor of colon/rectum
Mainly polyps
mainly adenocarcinomas
Define polyps
A circumscribed growth or tumour which projects above the surrounding mucosa
Difference between
non-neoplastic polyps and neoplastic polyps
**Need to biopsy to determine nature
non-neoplastic polyps
Simple overgrowths of mucosa, dont have malignant potential, not of clinical concern.
neoplastic polyps
Do have malignant potential, have to screen to identify and remove them at early stage
Types of Non Neoplastic Polyps and their characteristics
Hyperplastic polyps (superifical overgrowths of the bowel mucosa)
- Bengin
- Usually assymptomatic
- DO NOT have malignant potential
-Small, 3-6mm, common
Inflammatory Polyps
- Seen in IBD, overgrowth of mucosa
- Bengin
Types of neoplastic polyps
-characteristics
Adenomas
-Benign polyps with malignant potential (progress to adenocarcinomas)
-Mostly over 50 years age
- Familial predisposition
- Epithelial proliferation with variable degrees of dysplasia
Adenomas - 3 main types (based on appearance)
- Tubular adenomas
Most common, mostly tubular glands - Villous adenomas
Villous projections, often large and sessile - Tubulovillous adenomas Mixture of above
Polyps:
- general characteristics
Most asymptomatic
May bleed, mucosal discharge typically during bowl movements
If larger
- Altered bowel habit
- Bowel obstruction
Adenoma to Carcinoma Sequence
progression is associated we acquisition of a series of mutations in diff cancer causing genes
Benign PHASE
1. Hyperproliferation
a) Small
b) Large
2. Forms adenomatous polpys
3. Severe dysplasia (pre cancerous polyp)
CANCER phase
4. Adenocarcinoma
5. Cancer (invasion through bowel wall)
Polyps - main risk to turning into cancer
main risk for transformation is the size of the polyp and Degree of dysplasia
higher risk with villous adenomas than tubular
Adenoma to Carcinoma Sequence with associcated genes
Lecture SLide
Cause of Colorectal Cancer
Environmental lifestyle risk factors
1. Diet (high red meat, low fibre, high CHO)
2. Obesity
3.Alcohol
4. Smoking
Genetic / familial
Colon Cancer
- type of cancer
- located
Adenocarcinoma
Found caecum, ascending, transverse,
descending , sigmoid colon and rectum
Histology of colon cancer
Lecture Slide
Staging colon cancer
and prognosis determined by?
T = extent of invasion of bowel wall
N = number of lymph nodes involved
M = metastatic disease present or not
Prognosis determined by stage of tumour
Staging Colon cancer: T types
T1: Confined to mucosa
T2: Invasion through mucosa
T3: All the wat through bowel wall
T4: Region spread into lymph nodes
Clinical features of colon cancer
- Symptoms
- Right sided tumor feature
-spreads to
-Constitutional symptoms
Abdominal pain
mucous discharge
PR (rectal) bleeding
Change in bowel habit
Bowel obstruction
Right sided tumors: may present with iron def anameia due to occult bleeding (chronic small amounts of blood loss leads to the anamiea)
Spread to regional nodes, liver, lungs, bones
Constitutional symptoms: weight loss and malaise
Familial Polyposis Syndromes:
- What is it
- inhertiance type
-causes
Group of inherited polyposis syndromes
Autosomal dominant inheritance
Predisposition to malignant transformation In colon and other sites
Familial Adenomatous Polyposis:
- What is it
-genetic cause?
-inhertiance
- treatment
Multiple adenomas in colon and elsewhere in gut - most tubular adenomas
Usually evident adolescence
Transform into cancer
APC gene on chr 5q21
Autosomal dominant
Prophylactic colectomy - needs to remove whole colon due to so many polyps everywhere
Hereditary Nonpolyposis Colorectal Cancer (HNPCC)
-Inhertiance
-consider if?
- Progress
- Cause
Autosomal dominant inheritance
Consider if family history or young age of onset of cancer
Progress adenoma to carcinoma but no increase in polyps
Due to inherited mutation in DNA mismatch repair gene
