What is Cancer? Flashcards
How often is someone diagnosed with cancer in the UK?
Every 2 minutes
How many new cases were diagnosed every day in the UK in 2015?
990 cases
How often does someone die from cancer in the UK?
Every 4 minutes
What is the risk of of someone catching cancer in the UK if born after 1960?
1 in 2
What is the survival rate of cancer in England/Wales
50% survive disease for 10+ years
How many cancer cases in the UK are linked to lifestyle habits?
42% (4 in 10)
List 9 carcinogens that can increase the risk of cancer
- Smoking
- Obesity and poor diet
- Hormones
- Alcohol consumption
- Certain workplaces
- UV light from sun/sunbeds
- Infections and HPV
- Inherited genes
- Air pollution and radon
List 5 preventatives that can decrease the risk of cancer
- No smoking
- Reduced alcohol consumption
- Physical activity
- Healthy diet
- Less exposure to UV
What is cancer?
The name for a group of diseases characterised by different hallmarks
What are the 4 main stages of cancer?
- Abnormal cell proliferation
- Tumour formation
- Invasion of neighbouring normal tissue
- Metastasis to form new tumours at distant sites
Define abnormal cell proliferation
Cells that have lost the ability to control growth and therefore multiply rapidly
Define tumour formation
Has not been picked up by the immune system and has evaded cell death to form a clinically detectable tumour
Define invasion of neighbouring normal tissue
Cells of the tumour have been able to move around and migrate to different tissue
Define metastasis to form new tumours at different sites
The tumour cells that have invaded new tissue begin to form new tumours at these sites
How many different types of cancer have been classified according to their origin?
Over 200
What are carcinomas?
Cancers found in epithelial cells
What percent of cancers are carcinomas?
Approx 85%
What are sarcomas?
Cancers derived from mesoderm cells in bones and muscles
What are adenocarcinomas?
Cancers found in glandular tissues
What do carcinogens do to DNA?
Cause alterations, specifically mutations and deletions
What is carcinogenesis?
The formation of cancer where normal healthy cells are transformed into cancerous cells
What happens when the DNA mutations accumulate over time?
It represents the multi step process that is carcinogenesis
When does mutation accumulation in the DNA occur?
After the cells defence mechanism of DNA repair has been evaded
What happens when the DNA damage is severe?
Apoptosis is induced
What is apoptosis?
Process of planned cell death to eliminate unwanted cells
Can cancer cells evade DNA defence mechanisms?
If the system is over burdened, the possibility of cells escaping surveillance is increased
Does our ability to live longer affect our risk of cancer?
Yes as cancer risk increases with age
What are germline mutations?
Alterations in DNA through point mutations/deletions in egg/sperm cells which can then be inherited
What do germline mutations result in?
Inherited mutation in offspring which increases their risk of developing certain cancers later in life
How many cells are needed to form a primary tumour
Only 1 out of the 10^14 somatic cells in the body is used as it divides and produces many clonal cells to form a tumour
How many mutations in tumour cells are caused my somatic mutations
Almost all
How are tumour cells heterogeneous?
They have subclonal selection which allows a growth advantage allowing resistance and therefore heterogeneity
Is the cell mutation in the same type of cancer in two different people identical?
No, it depends on the tumour cells interaction with other tumour cells and the tumour microenvironment
What are the 4 steps of the cell cycle of normal cells?
- Proliferation (controlled division and growth)
- Differentiation
- Perform function
- Apoptosis (programmed cell death)
Where in the cell cycle does carcinogenesis occur?
Mutations in DNA affect proliferation, differentiation and apoptosis by causing rapid division of the cells into a tumour
What do normal genes do?
Regulate growth
What is an oncogene?
A proto-oncogene that has been mutated to signal uncontrollable growth such as cancer
What type of gene can be mutated into an oncogene?
A proto-oncogene
What is a tumour suppressor gene?
A gene that inhibits growth and tumour formation by releasing signals during phase G1 to stop or slow the cell cycle before phase S
What happens when a tumour suppressor gene is mutated?
Their function is disabled resulting in uncontrolled growth such as cancer
What happens when a tumour suppressor gene is mutated?
Their function is disabled resulting in uncontrolled growth such as cancer
How do cancer cells sustain proliferative signalling?
They are not dependant on growth factors to divide unlike normal cells and therefore can grow unregulated
How do cancer cells evade growth suppressors?
They have acquired mutations or gene silencing which interfere with inhibitory pathways used for normal cells
How do cancer cells avoid immune destruction?
They are able to shield themselves from immune attack and can actively immunosuppress the environment
How does the immune system respond to cancer cells?
- Protect from virus induced tumours
- Eliminate pathogens
- Identify and eliminate tumours
All through immune surveillance
What is cancer immunoediting?
The immunene system attempting to control cancer contested with the ability of some tumours still arising from cancer cells that have evaded the immune system
What are the 3 Es of cancer immunoediting?
Elimination, Equilibrium, Escape
What is elimination in cancer immunoediting?
The immune system is able to eradicate developing tumours
What is equilibrium in cancer immunoediting?
If there is incomplete removal, tumour cells remain dormant and enter equilibrium. The immune system exerts pressure to contain the tumour however some cells may mutate to survive this
What is escape in cancer immunoediting?
The expanding tumour population becomes clinically detectable
How is breast cancer diagnosed?
- Mammogram
- Ultrasound
- Biopsy
- Bone scan
- MRI
How is colon cancer diagnosed?
- Physical exam
- Blood in stool
- Colonoscopy
How is lung cancer diagnosed?
- Sputum cytology
- Biopsy
How is ovarian cancer diagnosed?
- Pelvic examination
- CA-125 assay
- Ultrasound
- CT
- MRI
How is prostrate cancer diagnosed?
- Digital rectal exam
- PSA levels
- Biopsy
How is pancreatic cancer diagnosed?
- Physical exam
- Biopsy
