INTRODUCTION TO CANCER Flashcards
What is cancer?
cellular disease caused by uncontrolled division of abnormal cells; arises from mutations in normal cell DNA
What are tumours and the types?
(lumps of tissue) form when abnormal/damaged cells grow when they shouldn’t
Types of tumours:
Cancerous (malignant)
Not cancerous (benign)
What is malignant tumours
cancerous - can spread in nearby tissue (invasion) & travel to distant organs to form new tumours (metastasis)
reasons of cancer? (5)
-Errors during cell division
-DNA damage due to carcinogens
-Loss of ability to eliminate damaged cells (decreases with age)
-Accumulation of mutations
-Hereditary
what are the different mutation types (2)
- somatic mutation (most common) - changes to DNA of somatic cells
-10% of cancer are hereditary (familial cancers) due to germline mutations
E.g. breast, colon, prostate - gremlin mutations: changes to DNA of germ cells; inherited from parent to offspring
(germ cells will become egg and sperm cells hence mutations will be passed on during conception)
What are the drivers of cancer?
Proto-oncogenes
tumour supressor genes
DNA repair genes
what are photo-oncogenes
involved in normal cell growth & division.
If mutated/overactivated, they cause cancer (oncogenes)
what are tumour suppression genes
involved in cell growth and division control
- if mutated cells divide uncontrollably
What do DNA repair genes do?
- fix damaged DNA
- if mutated, additional mutations and chromosomal changes accumulate and cells become cancerous
What are the features of normal cells (7)
Grow in response to growth signals
Respond to stop/death signals
Stop growing when encounter other cells; don’t move around the body
Blood vessels only grow when needed
Repair damaged chromosomes
Immune system eliminates damaged/abnormal cells
Make energy via;
Oxidative phosphorylation (aerobic respiration)
Anaerobic glycolysis
What are the features of cancerous cells (7)
Grow in absence of growth signals
Ignore stop/death signals
Spread in nearby tissues & travel to distant organs to form new tumours
Tell blood vessels to grow toward tumours (induce angiogenesis)
Accumulate mutations & chromosomal changes
Hide from the immune system; trick the immune system into helping them stay alive & grow
Rely on different nutrients; make energy in a different way
What are the emerging hallmarks
- avoiding immune destruction
- deregulating cellular energetics
what are the enabling characteristics
-tumour-promoting inflammation
-genome instability and mutation
What are the risk factors of cancer (8)
Older age
Family history
Tobacco
Alcohol
Viral infections
Obesity
Chemicals
Radiation
What are carcinogens
Harmful substances, radiation or radionuclides in the environment that promote carcinogens
They interact with DNA & induce mutations
Carcinogens are natural (aflatoxin) or manmade (asbestos, tobacco)
*Aflatoxin is produced by a fungus and sometimes found on stored grains.
What are the characteristics of benign tumours?
Small
Slow-growing
Non-invasive
Well-differentiated
Stay localised
Stay where they are
Can’t divide or metastasize
what are the characteristics of malignant tumours
Large
Fast-growing
Invasive
Poorly-differentiated
Metastasize
Infiltrate, invade, destroy surrounding tissue
Then metastasize to other parts of the body
What is hyperplasia
enlargement of organ/tissue; normal looking cells but increased numbers
E.g. prostatic hyperplasia
what is dysplasia
abnormal growth of cells/organs and or abnormal histology/structure
e.g. abnormal mole (can become melanoma)
what is carcinoma in situ
abnormal cells at original location, abnormal cells haven’t invaded
E.g. breast ductal carcinoma in situ
What are the non-cancerous tissue changes
- may develop into cancer if left untreated
- hyperplasia
- dysplasia
- carcinoma in situ
What are the cell type of cancers (7)
-carcinomas
-sarcomas
-melanomas
-gliomas & meningiomas
-lymphomas
-leukaemia
-myeloma
What are the order of events with non cancerous tissue changes
normal -> hyperplasia -> dysplasia -> cancer
What are types of cancer
- names based off of area/organ or origin & cell type
- solid tumours: abnormal masses without cysts or liquid area
- haematology malignancies (blood cancers) - generally don’t form solid tumours
- common cancers based on area: breast, lung, prostate, bowel
What are carcinomas
originate in skin, lungs, breast, & other organs and glands -> solid tumours
What are sarcomas:
(uncommon) arise in bone, muscle, fat, blood vessels, cartilage, or other soft & connective tissues–> solid tumours
What are melanomas
arise in melanocytes–> solid tumours
What are Gliomas & meningiomas
tumours of brain & spinal cord
*Melanocytes: cells that produce the skin-darkening pigment melanin
What are lymphomas
-blood cancers of immune system
-Affect lymphocytes–> can appear as solid tumours in lymph nodes of neck, chest, armpit, groin etc.
What is leukaemia?
blood cancers
Affect WBCs in bone marrow–> no solid tumours
What are myelomas
blood cancers
Affect plasma cells in bone marrow–> no solid tumours
*Plasma cells: WBCs specifically antibody-producing B cells
How is cancer diagnosed?
physical exam -> lab test/imaging/scan/biopsy
What occurs in physical exam
exam for lumps or abnormalities
E.g. organ enlargement, changes in skin colour
What are the lab tests?
E.g. on blood, urine, other body fluids
Complete blood count with unusual number of WBCs–> leukaemia
Tumour markers in blood- made by normal/cancer cells but high levels of cancer cells
E.g. high prostate specific antigen (PSA)–> prostate cancer
What are the diagnostic imaging?
X-rays: low dose radiation–> lung cancer
Mammography: low energy X-rays–> breast cancer
Computerised tomography (CT) scan: combines X-rays & computer processing to create 3D images; contrast material may be used
Ultrasound: high energy sound waves that echo off tissues
What is magnetic resonance imaging?
strong magnetic fields & radio waves; contrast agents may be used
What is a biopsy?
collection of samples of tissue or cells for lab testing
Samples can be collected with needle (bone marrow aspiration), endoscopy (colonoscopy) or surgery
What is PET scan and full name?
- positron emission tomography
-injected radioactive substances (tracers) e.g. fluorodeoxyglucose, to measure metabolic changes
What is a bone scan?
radioisotopes (e.g. 99mTc medronic acid) to detect abnormal areas/damage in bones–> bone or metastatic bone tumours
*For the PET scan, 18F-FDG is used as cancer cell uptake more glucose than normal cells
What are the hallmarks of cancer?
-Sustaining proliferative signalling-
-Inducing angiogenesis-
-Resisting cell death-
-Deregulating cellular energetics-
-Evading growth suppressors-
-Avoiding immune destruction-
-Genome instability & mutation-
-Activating invasion & metastasis- s
What is sustaining proliferative signalling match to description of capabilities of cancer
grow in absence of growth signals
how does cancer induce angiogenesis
tell blood vessels to grow towards the tumour
How does cancer cells resits cell death
ignore death signals
How does cancer deregulate cellular energetics
make energy in different ways and rely on different nutrients
how does cancer evade growth supressors
ignore signals telling them to stop growing and dividing
How does cancer avoid immune distruction
hide from immune system
how does cancer enforce genome instability and mutation
accumulate mutations and chromosomal changes
how does cancer activate invasion and metastasis
spread in nearby tissues and travel to distant organs to form new tumours
What is the meaning of hallmarks of cancer
how normal cells change into cancer cells
