colorectal cancer W7 Flashcards
colonic polyps features?
not all colonic polyps progress to adenocarcinoma
adenomas have the highest progression potential to adenocarcinoma
hyperplastic (metaplastic) polyps don’t have malignant potential
a special type of hyperplastic polyp called serrated polyp has some malignant potential
microscopic features of polyps - adenoma vs adenocarcinoma?
adenoma - dysplastic glands forming tubular and villous structures
adenocarcinoma - abnormal glands invading wall of colon with stromal reaction
cytological features of malignancy in tumour cells?
high nucleus/cytoplasm ratio
hyperchromasia (darkly stained nuclei)
pleomorphism (variable size/shape)
what is the adenoma-carcinoma sequence
the adenoma-carcinoma sequence refers to a stepwise pattern of mutational activation of oncogenes and inactivation of tumour suppressor genes that results in cancer
what is an oncogene
an oncogene is a gene that has the potential to cause cancer. in tumour cells, these are often mutated or expressed at high levels.
what is a tumour suppressor gene
a tumour suppressor gene is a gene that is involved in dampening the cell cycle or promotion of apoptosis or both. examples include inactivation of p53
what is the APC gene? function? what does deletion cause?
related to production of APC protein which is a tumour suppressor. APC gene is a negative regulator that controls beta-catenin concentrations and interacts with E-cadherin, which are involved in cell adhesion. deletion of APC cancer predisposes to cancer.
colorectal alarm features?
weight loss
rectal bleeding
anaemia, thrombocytosis
persistent diarrhoea (lack of day-day variability) in R side colon cancers (ascending colon and caecal tumours)
frequent nocturnal symptoms
new onset over 50 yrs
FHx bowel cancer
PMHx IBD
possible diagnoses of case:
64yr male, rectal bleeding, mild anaemia
haemorrhoids
colon polyps
colon cancer
inflammatory bowel disease
grading vs staging system for GI cancer?
grade - how patterns of cancer cells look under a microscope (normal/abnormal). high grade tumours norm spread/grow faster than low grade.
staging - stage of colorectal cancer is standard way for doctor to sum up how far the cancer has spread (TNM staging system)
TNM staging system explanation?
T - how far primary tumour has grown into wall and nearby organs
N - cancer spread to nearby lymph nodes
M - has cancer metastasized (spread to distant organs)
T staging (T1-T4?)
T1 - mucosa/submucosa
T2 - muscularis
T3 - serosa
T4 - nearby organs
risk factors for colorectal cancer?
diet high in red/processed meat
cooking meats at high temps
low fibre diet
obesity
physical inactivity
smoking, alcohol excess
family history of colorectal polyps/cancer
history of IBD
old age
where does the majority of bowel cancer cases occur?
rectum
then sigmoid
then caecum
colorectal cancer screening features?
identifying and treating pre-invasive disease (adenoma) and early invasive carcinoma
over age 50 routinely checked for occult blood (qFIT)
if positive - colonoscopy
