Cancer Therapies Flashcards
What are the standard therapies of cancer?
Surgery
Radiation therapy
Cytotoxic chemotherapy
Adjuvant therapy
How do you maximise efficacy of cancer treatment?
Integrate standard therapies w/ targeted therapies
What are the techniques to diagnose cancer?
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)
How do oncologists grade tumours?
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
Describe the types of clinical trial phases
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
What is co-morbidities?
Other medical conditions that influence the quality + quantity of life + ability to tolerate cancer treatments
What is adjuvant therapy?
Perioperative treatments given AFTER surgery
What is neo-adjuvant therapy?
Perioperative treatments given BEFORE surgery
Name 4 types of surgery for cancer
Diagnostic
Curative
Debulking
Palliative
What are the advantages of surgery as a cancer treatment?
Quick + effective
Curative (mostly)
Confirmation of excision
What are the advantages of surgery as a cancer treatment?
No guarantee of complete removal
May be in critical regions (e.g. brain)
Ineffective for metastasis
What is radical mastectomy?
Entire removal of breast, lymph nodes + muscle
What is lumpectomy?
Removal of tumour + rim of surrounding tissue only
What is a modified radical mastectomy?
Removal of tumour + lymph nodes but not muscle
What recently became the common way to deliver radiation?
linac (linear particle accelerator)
= can control beam of radiation
How is radiation measured?
In Gy (Gray) 1 Gy = 1 J/kg = 100 rads 1 rad (absorbed dosed) = 100 erg/g
What does radiation do inside the body?
Ionising radiation damages cells by ‘radiolysis’ (cleavage of chemical bonds) + subsequent dissociation of molecules, particularly water
Directly damages DNA -> indirectly damages proteins
What are the types of radiation?
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
What is the main problem of delivering radiation?
Radiation has to pass normal tissue
How to focus on tumour?
What is SBRT?
Stereotactic body radio therapy
= Stereotactic surgery (beams of radiation) combined w/ advanced 3D imaging
= Higher dose can be applied as it’s focused
What’s the difference bet. photon + proton radiotherapy?
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
What are adjuvants?
Harmlessprodrugswhich areconverted tocytotoxicmetabolites under certainconditions
What are bioreductives?
Prodrugs that are converted to cytoxic compounds under HYPOXIC conditions
What is photodynamic therapy (PDT)?
Prodrugs (photosensitisers) that are activated under certain wavelengths of light into cytotoxic agents
What type of tumour cells are highly resistant to radio + chemotherapy?
Hypoxic cells
= Can cause relapse
How do you target hypoxic cells?
Use bioreductives
Name an example of a bioreductive
AQ4N (banoxantrone)
AQ4N -> AQ4 (cytotoxic)
Adjuvant therapies = Combination of radiation/chemotherapy/surgery w/ other drugs
Bioreductives (e.g. AQ4N) w/ radiation can increase tumour growth delay
What is a side effect of AQ4N?
Patients turned pale blue
But have a very short half life
What are the advantages of radiation?
Quick + effective
What are the disadvantages of radiation?
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)
What are the disadvantages of chemotherapy?
Toxicity
- Typically target cycling cells
- May be less selective to tissue
Ineffective delivery
- Local variations in blood flow
Drug resistance
- Multiple reasons
