L24: Radiotherapy Flashcards
What is the method of radiotherapy
1) Damage the DNA within cancer cells and destroying their ability to reproduce
2) damaged DNA in cancer cells causes apoptosis
3) normal cells are able to repair themselves
What is the machine that delivers radiotherapy called
Linear accelerators
When is radiotherapy used
Radical: to treat cancer can be with or without chemotherapy
Adjuvant: after surgery to get rid of microscopic tumour cells
Neo-adjuvant: before surgery to shrink the size of tumour
Palliative: to manage symptoms such as bleeding and pain and increase QOL
In which cancer can radical radiotherapy be used in
Prostate Bladder Head and neck Gynae Lungs
In which cancer types can adjuvant radiotherapy be used in
Breast cancer
Prostate
Lungs
Which cancer can neoadjuvant radiotherapy be used for
Rectal cancer
If a patient has radiotherapy what is the process that they go through
1) have a CT scan to design and measure the patient so the radiotherapy hits the right spot and does not radiate unwanted parts
2) areas that you want to ignore have a lower dose delivered
3) radiotherapy is aimed at the correct spot each time so we have skin tattoos
What do radiotherapist need to consider when targeting tumours
Microscopic tumours that you cannot see around the tumour
What is the gross tumour volume
Cancer you can see at the scan
What is the gross tumour volume expanded by
Clinical target volume
What does the clinical target volume take into consideration
Microscopic tumours
What is the clinical target volume expanded to
Planning target volume
What is the planning target volume
Because the set up is not 100% precise, it depends on the location we are targeting which can change in size e.g the bladder
From the planning target volume what area is next
Exposed area
What is the exposed area
We cannot stop radiation at the line of planting target volume so there is an exposed area which gives the side effects
When we prescribe a radiotherapy what are the 2 factors considered
Grays
Fractions
What is gray
The measurement of the dose
What is the fraction
The number of visits for a treatment i.e the number of times the dose is divided into
How is energy transferred to the body
Via a photon interaction that generated the charged particles which damage the dna
What limits the dose that we can give
Normal tissue tolerance i.e the healthy tissue around the tumour
Why do we fraction a radiotherapy
1) repair: to allow normal tissue to repair itself
2) redistribution: the most radio sensitive part of the cell cycle is G2/M phase, when we fraction we increase the chance of cancer cells to process int the G2/M phase where they are radiosensitive
3) repopulation: cancer cells can repopulate when they are not being treated so if there is a break in radiotherapy they can cause problems
What are the 2 types of external radiation therapy
3D CRT
Intensity modulated radiation therapy
Name an example of internal radiation therapy that can be used for treating prostate cancer
Brachytherapy
How does internal radiation therapy work
You place a radioactive material into the tumour or surrounding tissue
What are the advantages of internal radiation therapy
Allows minimal radiation exposure to normal tissue so side effects are less
What are the disadvantages of internal radiation therapy
If there is cancer beyond the tumour cells it would not target them
With breast cancer how can radiotherapy be used after a mastectomy
Adjuvant radiotherapy
What would adjuvant radiotherapy require for breast cancer to stop metastasis
Chemotherapy or hormone therapy
Why isn’t radiotherapy good for metastasising cancer
Radiotherapy is localised to the primary site of the tumour
What can palliative radiotherapy be used for
Reduce:
Pain
Bleeding
What does palliative radiotherapy not do
Increase the survival rate
What are the acute side effects of radiotherapy
Fatigue
Nausea
Dermatitis
Mucositis: eating/ drinking, communicating, pain/mucus
What other side effects can radiotherapy give
Late side effects when radiotherapy has been stopped
What type of late side effects can radiotherapy give for breast cancer
Scarring
What late side effects can radiotherapy give for oesophageal cancer
Lung fibrosis due to scarring
What can type of late side effects can pelvic radiotherapy give
Bone pain or fragile bones
