Treatment of cancer Flashcards
Radiotherpay can be…
Direct
Indirect
Indirect radiotherpay forms
Super oxide free radicals
Aim of radiotherapy =
damage DNA/double-strand break –> apoptosis
Radiotherapy is usually delivered via a
Linear accelerator
Types of particle radiation =
Photon
Electron
Proton
Photon therapy advantages =
Skin sparing
Beam uniformity
Gray =
A unit of absorbed radiation equal to the dose of 1 joule of energy absorbed per 1 kg of matter (1 J/Kg)
SABR =
Stereotactic ablative radiotherapy
Stereotactic ablative radiotherapy
Specialised way of delivering radiotherapy. Uses small, very precisely targeted treatments. Minimises damage to surrounding tissue.
Brachytherapy =
Internal radiotherapy
Conditions needed for brachytherapy =
- Accessible, well-demarkated tumour w/o high risk of regional lymph node metastasis
2 types of complications of radiotherapy:
- Acute tissue reactions
2. Late tissue reactions
Acute tissue reactions usually occur =
In the middle of a long radiotherapy schedual
Acute toxicity in radiotherapy =
2nd week = mucosal reactions (e.g. mucositis)
5th week = skin reactions
Mucositis =
An intensity-limiting side effect for aggressive schedules. May mean patient can’t feed themselves during rounds
Late toxicity tends to be
Permanent
Late toxicity in radiotherapy occurs in cells with:
Low turnover (fibroblasts, neurons)
Late toxicity develops within
Months - years
Most common late side effect of radiotherapy
Xerostomia
Xerostomia
Dry mouth
Ex of late toxicity reactions to radiotherapy:
- Xerostomia
- Dental caries
- Fibrosis
- Soft-tissue necrosis
- Nerve tissue damage
- Ocular: catarcts, optic neuropathy, retinopathy
- otological
- CNS
At what weight do tumour cells become clinically apparent?
1g
Log-kill hypothesis of chemotherapy =
For a given dose of chemo in a given tumour, only a fraction of tumour is killed. Therefore, several courses is needed.
Chemotherapy works in cells that’re…
Cycling
Chemo works more rapidly on
Proliferating areas
Ex of proliferating areas:
- Hair
- Skin
- GI mucosa
- Bone marrow
Uses of chemotherapy:
- Curative
- Adjuvant
- Neoadjuvant
- Palliative
Curative chemo:
Chemo is main treatment
Adjuntive chemo:
Used to mop up cancer cells after treatment
Neoadjuvant chemo:
Given before surgery
Palliative chemo:
Improve QOL
2 types of chemo toxicity:
- Acute: due to effects on normal proliferating cells
2. Chronic: end organ damage
Common acute side effects of chemo:
- Bone marrow: decrease WBC, RBC, platelet
- Alopecia
- Stomatitis, mucositis, nausea, vomiting
- Extraversion
Extraversion =
Leakage of IV drugs into surrounding tissues.
Drug resistance can be:
Primary or secondary
Primary drug resistance:
Tumour grows from start/never responds to chemo
Secondary drug resistance:
Intital response to chemo, tumor then grows again
MDR-1 gene is involved in:
Drug reflux
Drugs that reverse MDR
Verapamil
Guanidine
Cyclosporine
Ex of alkylating agents:
Nitrogen mustard gases
Alkylating agents MoA
Add alkyl group to guainine. Covalent bond/cross link - arrest cell cycle
Ex of antimetabolite
Methotrexate
Methotrexate disrupts
Folate metabolism (DHFR)
Cisplatin has a similar effect to
Alkylating agents
Tyrosine kinases are involved in…
Growth factor replication signal transduction
