Cancer Flashcards
How many new cancer cases are there per annum?
300,000
What is the definition of a tumour?
The abnormal multiplication of cells
What is the difference between a Benign, Malignant and Metastatic tumour?
Benign - local multiplication of cells within a tissue
- no clinical impact
Malignant - tumour cells become “disorganised” and spread locally within a tissue
Metastatic - tumour cells escape from their host tissue and invade other organs
What is the Gleason grading of prostate tumours?
Looking at how disorganised the pathology is, and then grading how far along the cancer has gotten.
How do tumour cells regulate the behaviour of normal counterparts to create more of the tumour?
Through tumour angiogenesis
- tumour cells induce the growth and invasion of new blood vessels which infiltrate and oxygenate the tumour
What are the differences between normal and tumour cells?
- requirement for growth factors
- does not senesce
- abnormal shape and requirement for attachment
- invasive behaviour
- genome instability
- release agents which modify tumour environment
What are the 6 main things “hallmarks” that need to happen that turn a normal cell into a cancer cell?
- evading apoptosis
- self-sufficiency in growth signals
- insensitivity to anti-growth signals
- tissue invasion & metastasis
- limitless replicate potential
- sustained angiogenesis (formation of new blood vessels)
What Geographic variation is seen in cancer incidence and death rates?
Melanoma (skin cancer) country of highest risk is Australia but lowest is Japan.
- exposure to UVP in radiation cause for high incidence
For prostate cancer, the highest is the U.S but lowest is China.
- Prostate cancer is low in Osaka, but then the family is moved to Hawaii, rate increases.
How would you measure the efficacy of a cancer therapy?
- elimination of tumour (no relapse)
- prolongation of life span
- relief of symptoms
- reduction in cost of treatment
What are 3 approaches to cancer therapy?
- Physical removal of the tumour
- Drugs that kill the tumour
- Drugs that modify the host response to the tumour
through: - surgery
-radiotherapy
-chemotherapy - host modifiers
- targeted therapeutics
What are some desirable features of an anti-cancer therapy?
- effective
- no impact on normal host cells
- minimal toxicity
- inability to develop resistance
- easy to administer (no need for prolonged care with specialised doctors & nurses)
What are the benefits of surgery?
- highly effective at reducing tumour mass
- one time treatment
- no possibility of resistance
(breast cancer - lumpectomy)
What are the disadvantages of surgery?
- tumour has to be surgically accessible
- cannot treat metastatic disease
- requires knowledge of the tumour
- requires sophisticated facilities and expertise (Expensive)
- potentially traumatic and dangerous
What are the benefits of radiotherapy?
- effective at reducing tumour mass
- is topologically precise
- can treat tumours that cannot be surgically accessed
- bulk reduction of the tumour
How does radiotherapy work?
Kills cells by irreversibly damaging DNA beyond repair
What are the disadvantages of radiotherapy?
- significant host damage as it is not tumour specific, kills all cells
- resistance can occur
- limited effect on slowly dividing cells
- requires expensive facilities
How does chemotherapy work?
use of compounds that kills cells that are rapidly dividing
- tumour responds by proliferating more of the cells that werent killed
- repeated treatment progressively kills the tumour growth fraction
(cisplatin)
What are the benefits of chemotherapy?
- can be very effective in eliminating tumour mass
- often used after surgery
- is systemic in effect (drug connected to a drip so can go anywhere in the body needed)
- cheap and easy to deliver
- has palliative effect (patients have a better quality of life than before chemo)
What are the disadvantages of chemotherapy?
- severe toxic effect on dividing host cells
- does not eliminate slowly growing tumour cells
- resistance to drug can occur
- variable effectiveness between patients
How do host cell modifiers work?
Target the host cell to:
- stop supporting tumour growth (inhibit the growth of blood vessels)
- kill the tumour (inducing the immune system to kill the tumour) (CART Therapy)
- palliative effects (counteracting side effects such as pain, anemia)
What are the disadvantages of host cell modifiers?
- very expensive
- delivery of effective dose to tissues is uncertain
- host cell response can be toxic
- variable responses in patients
- counteracts effects of chemotherapy
How do targeted therapeutics work?
- identify specific molecular features of the tumour (e.g mutation)
- inhibit the biochemical activity of the target molecule
- exploits the hallmarks of cancer paradigm
- personalised therapy based on tumour genotype
Give examples of some targeted therapeutics.
Herceptin
- antibody that binds to the HER2 receptor in abnormal breast cancer cells
Gefitinib (Iressa)
- compounds that inhibits signalling via EGF receptors in non small cell lung cancers
What are the disadvantages of targeted therapeutics ?
- very expensive to develop and deliver
- excellent responses in subset of patients but overall impacts are modest
- acquisition of drug resistance
- different tumour types differ in response to the same drug
