Cancer Flashcards
What is a carcinoma?
Disorderly growth of epithelial cells that invade adjacent tissues and spread vis the lymphatics and bloodstream to other parts of the body.
What does it mean that most cancers are monoclonal?
They are derived from a single cell mutation.
How to cancer cells grow and divide?
Mitosis
How do some cancer cells escape chemotherapy treatment?
They hide within the non proliferating stage of mitosis and then recover and re-cycle in the body later on.
Give some properties of cancer cells?
Increased growth factor secretion Increased oncogene expression Loss of contact inhibition Loss of tumour suppressor genes. Frequent mitoses
What are oncogenes?
Genes that programme for cancer. Accelerate cell division.
Which type of cancer normally causes the death in a patient?
Cancer that has metastases rather than the primary cancer.
What are some causes of cancer
Chemical carcinogens Physical carcinogens Viral carcinogens Growth factors Oncogenes Metastasis
Give some examples of a chemical carcinogen?
Polycyclic hydrocarbons
Nitrogen mustard
Alcohol and smoking
Give some examples of physical carcinogens?
Ionising radiation
Mechanism - chromosome translocation, gene amplification, oncogene activation.
Give some examples of viral carcinogens?
Herpes virus
Papillomavirus
Retroviruses
Hepatitis B
What do oncogenes do?
Involved in the promotion of cancer. They are transformed genes and promote the positive regulators for growth.
Give some examples of growth factors?
Polypeptide molecules.
VEGF - vascular endothelial growth factor.
What is the normal function of a tumour suppressor gene?
Acts as a transcriptional regulator:
Promotes DNA repair, apoptosis and cell differentiation.
The cell’s brakes for cell growth.
How do cancer cells induce the alteration of tumour suppressor genes?
Induced by DNA damage and hypoxia
What are the properties if metastasis?
Not random
Cascade of limited sequential steps
Involves humour-host interactions
Survival of the fittest pertains
What are the main stages within invasion and metastasis?
Tumour invades through the basement membrane.
Moves into extracellular matrix/connective tissue/surrounding cells
Invades blood vessels
Tumour cells ‘arrested’ in distant organ
What is angiogenesis?
The formation of new blood vessels.
What is the role of angiogenesis in cancer.
Key factor in the maintenance and progression of malignant tumours.
A new blood vessel must form before a tumour can reach < 2mm in diameter.
It also provides a route for the cancer to spread and enter the circulatory system.
What is the role of VEGF?
VEGF normally binds to receptors one the surface of vascular endothelial cells. This binding activates the signalling pathways that lead to growth, proliferation and migration of endothelial cells - increasing cancer.
What is the function of Avastin?
Avastin is an anti-VEGF drug that prevents VEGF from interacting with its receptors. ultimately leads to a reduction in microvascular growth, inhibits progression of metastatic disease and reduces intratumoral pressure, which may improve the delivery of cytotoxic agents.
What percentage of cancer patients have metastases?
65%
How does the immune system not recognise foreign cancer cells?
Cancer cells can hide from T cells by the PDL-1 ligand on tumour cells binding with PD1 (programmed death receptor) on T lymphocytes. This suppresses the T cells and they become blinded.
Where do somatic mutations occur?
Occur in nongermline tissues
Are nonheritable
E.g breast
Where do germline mutations occur?
Present in egg or sperm
Are heritable
Cause cancer family syndromes
(All cells affected in offspring)
What is a Proto-oncogene?
Normal gene that codes for proteins to regulate cell growth and differentiation.
What is the two-hit hypothesis?
Cancer arises when both brakes fail
Cancer is the result of accumulated mutations to a cell’s DNA. Both genes need to be affected.
What is the role of MisMatch Repair (MMR)?
Corrects errors that spontaneously occur during DNA replication like single base mismatches or short insertions and deletions.
What is micro satellite instability?
MSI is the phenotypic evidence that MMR is not functioning normally.
Define benign?
Lacks ability to metastasize.
Rarely or never become cancerous.
Can still cause negative health effects due to pressure on other organs.
What is a dysplastic tumour?
‘Benign’ but could progress to malignancy.
Cells show abnormalities of appearance & cell maturation. Sometimes referred to as ‘pre-malignant’.
Define malignant?
Able to metastasize.
What are de novo mutations?
New mutations that occur within the germ cell of the parent. No family history of hereditary cancer syndrome
What are some features of retinoblastoma?
Most common eye tumour in children.
Occurs in heritable and nonheritable forms
What are the risk factors for breast cancer?
Ageing Family history Early menarche Late menopause Nulliparity - not had children Oestrogen use Dietary factors (eg: alcohol) Lack of exercise
What are the risk factors for colorectal cancer?
Ageing Personal history of CRC or adenomas High-fat, low-fibre diet Inflammatory bowel disease Family history of CRC
