Oncology Flashcards
What are the known causes of:
Lung cancer
Burkitt’s lymphoma
Leukaemias
Lung: cigarette smoking
Burkitt’s: EBV
Leuk: Radiation
What are the classes of aetiological agents?
Inherited Chemical Physical Diet Drugs Infective Immune deficiencies
What are the currently known gene mutations that cause types of cancer?
BRCA1 & BRCA2
NAPC
Von-Hippel Lindau syndrome
p53
What types of chemicals cause certain cancers?
Cigarette smoke: Lung cancer Aromatic amines: Bladder cancer Benzene: Leukaemia Wood dust: Nasal adenocarcinoma Vinyl Chloride: Angiosarcomas
How do chemicals cause cancer
Damage cellular DNA
Induce mutations in oncogenes & tumour suppressor genes
How does smoking cause cancer?
Cause specific mutations in the p53 tumour suppressor gene.
How does radiation exposure cause cancer?
Increasing DNA damage leading to the accumulation of mutations in tumour-suppressor genes and oncogenes.
In radiation exposure, what is the risk of tumour development associated with?
- Level of exposure: Dose dependant, accumulation of an isotope in a tissue may lead to tumour formation (e.g iodine & thyroid)
- Radiation source: High energy radiation (electrons/photons) more carcinogenic than x-rays. UV light damages the skin (malignant melanoma)
How does a low fibre diet cause cancer?
A decrease of transit time through the bowel thereby increasing exposure to carcinogenic substances.
How do drugs cause cancer?
Cytotoxic drugs induce DNA damage and are associated with an increased risk of malignancy. The effect is dose dependent.
(e.g topoisomerase inhibitors & acute leukaemia)
What infections can lead to cancer?
- HPV: Cervical & anal cancers
- EBV: Non-Hodgkin’s lymphoma
- Hep B: Hepatocellular cancer
- Retrovirus: T-cell lymphomas
- H.Pylori: MALT tumours
How does HPV cause cancer?
E6 protein produced by HPV16 bids to & inactivates p53 protein.
Dysregulation of cell cycle & apoptotic pathways
Malignant transformation of epithelial cells infected
How does EBV cause cancer?
Most common caused by EBNA
14:8 translocation- proto-oncogene ‘c-myc’ on Chr8 is transcriptionally controlled by control elements of immunoglobulin genes on Chr14
How does Retrovirus cause cancer?
Integration into cellular genome
Causes abnormal overexertion of oncogenes
What tests need to be done to diagnose cancer and then confirm the diagnosis?
BIOPSY: Either of a superficial mass or by endoscopic techniques
HISTOLOGY: Needed to treat a cancer radically
How is cancer staged?
TNM staging
Tx: Primary tumour cannot be assessed
T0: No evidence of primary tumour
Tis: Carcinoma in situ
T1/2/3/4: Increasing size and/or local extent of the primary tumour
NX: Regional cannot be assessed
N0: No regional lymph node mets
N1/2/3: Increasing involvement of regional lymph nodes
MX: Presence of distant mets cannot be assessed
M0: No distant mets
M1: Distant mets
How are tumours graded?
Histologically done
GX: Grade of differentiation cannot be assessed
G1: Well differentiated: Similarities remain to normal tissue of the organ of origin
G2: Moderately differentiated
G3: Poorly differentiated- bizarre cells
How can imaging be used in cancer medicine?
Diagnosis Staging (CT= chest & abdo malignancies, MRI= bone & soft tissue) Response assessment Follow-up Screening (mammography)
How is the RECIST system defined?
Response to treatment
Complete response: No disease detectable radiologically
Partical response: All lesions shrunk by at least 30% but disease still present
Stable disease: <20% inc in size or <30% dec in size
Progressive disease: New lesions/lesions inc >20%
What are the risks associated with CT?
-Radiation exposure: risk of inducing malignancies
What is MRI the gold standard of imaging tumours for?
Neurospinal
Rectal
Prostate
Musculoskeletal
What are contraindications for MRI scanning?
Pacemakers, implantable cardiac defibs
Metallic foreign bodies (eye or brain)
Vascular clips, surgical staples
What tumours can USS detect?
Metastases in solid ‘visceral’ abdominal organs
What tumours can be detected through nuclear medicine?
Bone scintography: Principle investigation for bone mets
Technetium
Radioiodine
What investigations should be done in metastatic disease of unknown primary?
Bloods: FBC,U&E, LFT, Ca, LDH Tumour markers: aFP, bHCG Urinalysis CXR CT: Chest, abdo, pelvis
What specific investigations can be done in patients with cancer?
Myeloma screen = lytic bone lesions Endoscopy= Direct towards symptoms PSA= Men Ca125= Women w/peritoneal malignancy/ascites Testicular USS= Men w/germ cell tumours Mammogram= Women w/signs of breast Ca
