Aetiology, imaging and tumour markers Flashcards
What is the guardian of the genome
p53 - tumour suppressor gene
What does cigarette smoke act as a carcinogen
Carcinogens in cigarette smoke cause specific mutations in p53 tumour suppressor gene
What cancer are aromatic amine associated with?
Bladder cancer
What cancer are benzenes associated with
leukaemia
what cancer is wood dust associated with
nasal adenocarcinoma
what cancer is vinyl chloride associated with?
Angiosarcomas
What does radiation increase the risk of cancer?
Increases DNA damage leading to the accimulation of mutations in tumour-suppressor genes and oncogenes.
In terms of radiation what 2 factors is tumour development associated with?
Radiation source
Level of exposure
What sort of cancer are low fibre western diets associated with
colorectal carcinomas
what sort of cancer is the smoked food eaten in Japan associated with
Gastric carcinomas
How do low fibre diets cause cancer
decreased transit time through the bowel therefore increasing the exposure to carcinogenic substances
what type of drugs are associated with increase in malignancy
Cytotoxic drugs - induce DNA damage
How does HPV cause cancer
the E6 protein produced by HPV16 binds to and inactivated p53 protein, this causes dysregulation of the cell cycle and apoptotic pathways and subsequent malignant transformation of epithelial cells infected.
what cancers are associated with the sexual transmission of HPV
cervical and anal carcinoma
what type of cancer is EBV associated with
Non-Hodgkins lymphoma and other lymphomas
how does EBV cause cancer
Most common genetic abnormality caused by EBNA, a 14:8 translocation in which the proto-oncogene c-myc on Ch8 becomes transcriptionally controlled by the control elements of immunoglobulin genes on Ch14
What cancer is Hep B virus associated with
hepatocellular carcinoma (100 x risk)
How can retroviruses cause cancer
through integration into the cellular genome retroviruses can cause abnormal overexpression of oncogenes
what cancer is H. pylori associated with?
mucosal associated lymphoid tissue (MALT) tumours
what immunodeficiency is associated with increased risk of tumours
T cell deficiencies
what is the key element for diagnosis of cancer
Biospy
What does TNM stand for
Tumour, node, metastasis
In staging, what does TX mean
Primary tumour cannot be assessed
In staging what does T0 mean
No evidence of primary tumour
in staging, what does Tis mean
Carcinoma in situ
In staging what does T1, T2, T3, T4 mean
Increasing side and /or local extent of the primary tumour
in staging what does NX mean
regional lymph nodes could not be assessed
In staging, what does N0 mean
No regional lymph node metastasis
In staging, what does N1, N2, N3 mean
increasing involvement of regional lymph nodes
in staging, what does MX mean
Presence of distant metastasis cannot be assessed
in staging what does M0 mean
No distant metastasis
in staging what does M1 mean
distant metastasis
In colorectal cancer what does Tis mean
Carcinoma in situ: intraepithelial or invasion of lamina propria
in colorectal cancer, what does TI mean
Tumour invades submucosa
in colorectal cancer, what does T2 mean
tumour invades muscularis propria
in colorectal cancer, what does T3 mean
tumour invades through muscularis propria into subserosa or into non-peritonealised pericolic or perirectal tissues
in colorectal cancer, what does T4 mean
tumour directly invades other organs or structures and/or perforates visceral peritoneum
in colorectal cancer, what does NI mean
metastasis in 1 to 3 pericolic or perirectal lymph nodes
in colorectal cancer, what does N2 mean
metastasis in 4 or more pericolic or perirectal lymph nodes
what does grade mean in cancer
this is histologically, to what extent the tumour resembles normal tissue or has a bizarre appearance
In grading what does GX mean
grade of differentiation cannot be assessed
in grading, what does G1 mean
well differentiated: similarities remain to normal tissue of the organ of origin
In grading what does G2 mean
moderately differentiated
In grading, what does G3 mean
poorly differentiated, bizarre cells
What do higher grades mean in terms of recurrence
Higher grades have a higher risk of recurrence locally and of being of higher stage including development of secondaries
What is the purpose of staging and grading
to indicate prognosis and give the appropriate treatment
what do lymph node metastasis indicate?
they are a powerful indicator of probable systemic blood borne metastases
what is the standard imaging tool for the evaluation of chest and abdominal malignancies
CT scan
When is MRI useful in cancer imaging
In bone and soft tissue lesions, and regions where bone causes artifact in the CT appearance eg pelvis or post. fossa of the brain
What is the RECIST system
objective tool used to measure response to treatment
in the RECIST system, what defines complete response
no disease detectable radiologically
in the RECIST system, what defines partial response
all lesions have shrunk by at least 30%, but disease is still present
in the RECIST system, what defines stable disease
less than 20% increase in size or less than 30% decrease in size
in the RECIST system, what defines progressive disease
new lesions or lesions that have increased in size by more than 20%
is routine follow up imaging routine practice
no - there is no proven benefit
what are the qualities of a tumour marker
highly sensitive so that few people are missed AND highly specific so that few people are falsely labeled as having the disease
what is sensitivity of a marker
the ability to detect those with a certain disease. if 100 people have the disease and the marker is elevated in only 95 = sensitivity 0.95
what is specificity of a marker
its ability to accurately define those who are disease free. If in 100 disease free people the marker is negative in only 90 the specificity of the test is 0.90
which tumours is MRI scanning the gold standard for
neurospinal, rectal, prostate and MSK tumours
what is real time MR
uses the changes in MR appearances over time or after contrast agents and are of increasing use in diagnostic work such as assessment of breast masses
under what circumstances can you not have an MRI
pacemaker, implantable cardiac defibulators, metal foreign bodies. Metallic foreign bodies in the brain or eye are an absolute contraindication eg vascular clips, surgical staples and metallic shards following trauma
in terms of tumours what can doppler ultrasound be used to assess
tumour blood flow
what can USS be used for in cancer diagnostics
ultrasounded guided biopsy (real-time guidance)
what is bone scintography (bone scan) used for
skeletal masses
what scan are PET scans usually merged with
CT scans, to map functional images with detailed anatomy
what does PET scan stand for
Positron emission tomography
how does a PET scan work
detects high energy photons emitted by short-lived radioisotopes which can be chemically tethered to molecules such as glucose or somoatostain to form a tracer.
how does PDG-18 work in PET -CT scans
it is rapidly taken up in very metabolically active cells such as malignant cells or neurons.
when is PDG-18 often used
where radical treatment appears possible but has high mortality and/or morbidity
what are tumour markers
substances produced either by, or in response to a tumour and are present in blood or other tissue and can be quantified
what benign conditions can CA125 be elevated in
endometriosis, menstruation and pregnancy
what does marked elevated in PSA in a man with disseminated bone mets diagnostic of
prostate cancer
what tests should young males with metastasis have
serum LDH, alphaFP, beta-hCG - to diagnose chemo sensitive and potentially curable germ cell tumours.
what is one of the most clinically useful features of tumour markers?
indicate response to treatment, reduction suggestive of response
what is the most common use of CEA tumour marker
colorectal cancer
what is CEA
a cell surface antigen also expressed in a variety of normal tissues
what other things can cause elevated CEA
smoking, IBD, hepatitis, pancreatitis or gastritis
what s the level of CEA in a normal person who is a non-smoker
<5ng/ml
what is the tumour marker CA125 used for
ovarian cancer
what is CA125
antigen expressed on the surface of ovarian cells
what CA125 level is suggestive of cancer
> 200 U/ml
what other cancers can CA125 be raised in
pancreatic (59%) lung (32%) colorectal (21%) breast cancer (12%) usually when these are disseminated in to the abdo cavity
what cancers is alpha fetoprotein (alphaFP) raised in
hepatocellular carcinoma
cancers containing yolk sac elements
what is the level of alpha FP in normal individuals
undetectable