Cancer Therapies

Question 1

What are the standard therapies of cancer?

Answer 1

Surgery
Radiation therapy
Cytotoxic chemotherapy
Adjuvant therapy

Question 2

How do you maximise efficacy of cancer treatment?

Answer 2

Integrate standard therapies w/ targeted therapies

Question 3

What are the techniques to diagnose cancer?

Answer 3

Screening (established)
= Pap smear (histology based)
= Mammograms (look for lesions)
= Colonoscopy

Screening (controversial)
= CT scan (more expensive, false positives, not always picked up, don’t know if fast/slow growing)

Biomarkers
= PSA (prostate specific antigen) (highly prone to error, false positives)
= CEA
= Predictive biomarkers like HER2 + BRCA1 (more associated w/ cancer type)

Question 4

How do oncologists grade tumours?

Answer 4

TNM criteria

T (Tumour size):
T1 = Small + contained
T2 = Larger + contained
T3 = Any size + near airway, heart
T4 = Any size + in airways, heart or oesophagus

N (Lymph nodes):
N0 = No cancer cells present
N3 = Cancer cells present (particularly in axillary nodes)

M (Metastases):
M0 = No spread
M1 = Has spread

Question 5

Describe the types of clinical trial phases

Answer 5

Type 0:
= 10 - 20 people
= Many cancer types tested
= To test low doses for toxicity
= Not randomised

Type 1:
= 10 - 50 people
= Many cancer types tested
= To test for side effects
= Not randomised

Type 2: 
= 10 - 100 people
= 1/2 cancer types tested
= To test side effects + efficacy
= Randomised

Type 3: 
= 100s - 1000s people
= Usually 1 cancer tested
= To compare w/ existing treatment
= Usually randomised

Type 4:
= 10s - 1000s people
= Usually 1 cancer tested
= To test for long term effects
= Usually randomised

Question 6

What is co-morbidities?

Answer 6

Other medical conditions that influence the quality + quantity of life + ability to tolerate cancer treatments

Question 7

What is adjuvant therapy?

Answer 7

Perioperative treatments given AFTER surgery

Question 8

What is neo-adjuvant therapy?

Answer 8

Perioperative treatments given BEFORE surgery

Question 9

Name 4 types of surgery for cancer

Answer 9

Diagnostic
Curative
Debulking
Palliative

Question 10

What are the advantages of surgery as a cancer treatment?

Answer 10

Quick + effective
Curative (mostly)
Confirmation of excision

Question 11

What are the advantages of surgery as a cancer treatment?

Answer 11

No guarantee of complete removal
May be in critical regions (e.g. brain)
Ineffective for metastasis

Question 12

What is radical mastectomy?

Answer 12

Entire removal of breast, lymph nodes + muscle

Question 13

What is lumpectomy?

Answer 13

Removal of tumour + rim of surrounding tissue only

Question 14

What is a modified radical mastectomy?

Answer 14

Removal of tumour + lymph nodes but not muscle

Question 15

What recently became the common way to deliver radiation?

Answer 15

linac (linear particle accelerator)

= can control beam of radiation

Question 16

How is radiation measured?

Answer 16

In Gy (Gray)
1 Gy = 1 J/kg = 100 rads
1 rad (absorbed dosed) = 100 erg/g

Question 17

What does radiation do inside the body?

Answer 17

Ionising radiation damages cells by ‘radiolysis’ (cleavage of chemical bonds) + subsequent dissociation of molecules, particularly water

Directly damages DNA -> indirectly damages proteins

Question 18

What are the types of radiation?

Answer 18

ERBT (external beam radiotherapy)
= Source of beam is outside
= Most common

Brachytherapy
= Source is internal + focused 
= Seeds loaded w/ radioactive implant
= For certain types of cancers
( bladder, head + neck, melanomas)

Radionuclides
= Radioisotopes injected intravenously
= Tagged to go to certain tumour tissues
= Least common

Question 19

What is the main problem of delivering radiation?

Answer 19

Radiation has to pass normal tissue

How to focus on tumour?

Question 20

What is SBRT?

Answer 20

Stereotactic body radio therapy
= Stereotactic surgery (beams of radiation) combined w/ advanced 3D imaging
= Higher dose can be applied as it’s focused

Question 21

What’s the difference bet. photon + proton radiotherapy?

Answer 21

Photon
= Passes through tissues before + after tumour

Proton
= Focused (doesn't pass tumour)
= Fewer healthy cells damaged
= Doesn't work for some cancers
= Not approved - No randomised clinical trials to show it works better than photons

Question 22

What are adjuvants?

Answer 22

Harmlessprodrugswhich areconverted tocytotoxicmetabolites under certainconditions

Question 23

What are bioreductives?

Answer 23

Prodrugs that are converted to cytoxic compounds under HYPOXIC conditions

Question 24

What is photodynamic therapy (PDT)?

Answer 24

Prodrugs (photosensitisers) that are activated under certain wavelengths of light into cytotoxic agents

Question 25

What type of tumour cells are highly resistant to radio + chemotherapy?

Answer 25

Hypoxic cells

= Can cause relapse

Question 26

How do you target hypoxic cells?

Answer 26

Use bioreductives

Question 27

Name an example of a bioreductive

Answer 27

AQ4N (banoxantrone)

AQ4N -> AQ4 (cytotoxic)

Question 28

Adjuvant therapies = Combination of radiation/chemotherapy/surgery w/ other drugs

Answer 28

Bioreductives (e.g. AQ4N) w/ radiation can increase tumour growth delay

Question 29

What is a side effect of AQ4N?

Answer 29

Patients turned pale blue

But have a very short half life

Question 30

What are the advantages of radiation?

Answer 30

Quick + effective

Question 31

What are the disadvantages of radiation?

Answer 31

Can cause side effects (nausea, hair loss (as radiation targets rapidly dividing cells), tissue necrosis)

Limited by tissue tolerance/resistance (e.g. kidneys)

Risk of relapse

Increase risk of metastasis (not conclusively proven yet)

Question 32

What are the disadvantages of chemotherapy?

Answer 32

Toxicity

• Typically target cycling cells
• May be less selective to tissue

Ineffective delivery
- Local variations in blood flow

Drug resistance
- Multiple reasons