Chemotherapy and Radiotherapy, Targeted Biological Therapies Flashcards
Define “Brachytherapy”
Brachytherapy is a form of radiotherapy where a sealed radiation source is placed inside or next to the area requiring treatment
What are the advantages of Brachytherapy?
- Greater deliverable dose and continuous low dose rate
2. Good for hypoxic and slow proliferating tumours. 3. Shorter treatment times
What is the limitation of Brachytherapy?
Tumour must be accessible
Mucosal acute tissue reactions (Mucositis) typically begin when following radiotherapy?
Within the second week of radiotherapy
Skin acute tissue reactions typically begin when following radiotherapy?
Within the fifth week of radiotherapy
What is acute toxicity defined as in terms of time-frame?
Occurring less than 90 days post treatment
What is the most common late tissue reaction observed after radiotherapy?
Xerostomia (dry mouth)
Tumours must go through how many Doublings in the pre-clinical phase before it becomes the size of 1g?
30 Doublings
Tumours must go through how many Doublings in the clinical phase before it increases in size from 1g to 1kg?
10 Doublings
State two broad ways of delivering radiotherapy to treat cancer patients
External Beam
Brachytherapy
What is neo-adjuvant chemotherapy?
Chemotherapy given pre-surgery to downgrade a tumour
Why might some cancers be resistant to chemothapies?
Most chemotherapy works within the cell cycle. For cancers to be treated it must remain in the cyclic phase, and only when it is in G0 (the resting phase) does it become resistant to treatment
What is the mechanism of action for 5-Fluorouracil for treatment of cancer?
Thymidylate sythase inhibitor, thus preventing DNA replication
What is the mechanism of action for Bleomycin for treatment of cancer?
Causes DNA breaks
What is the mechanism of action for Cisplatin and Mitomycin for treatment of cancer?
Both are alkylating agents, causing DNA cross-linking
