Radiotherapy

Question 1

What is radiotherapy?

Answer 1

A highly regulated delivery of ionising radiation

Question 2

How does radiotherapy treat cancer?

Answer 2

It damages the DNA of the cancer cells (can also affect normal cells producing side effects in the treatment area)

Direct DNA damage or indirect - radiation causes free radical production, which causes DNA damage and cell death

Question 3

What different types of ionising radiation are used in the treatment of cancer?

Answer 3

Electrons
Photons (x rays)
Proton beams

Question 4

What types of radiotherapy are there?

Answer 4

External beam - most common

Brachytherapy - either as a boost or primary treatment, a sealed radiation source placed inside or next to area requiring treatment

Systemic treatment - radioactive substances injected/swallowed e.g iodine 131 radioisotope used for thyroid cancer

Question 5

Brachytherapy is used in what cancer types?

Answer 5

Prostate

Cervical

Question 6

What is the aim of RT?

Answer 6

Deliver highest dose possible to tumour

Minimise dose to surrounding ‘normal tissue’

Question 7

What are radiosensitisers?

Answer 7

Agents that make radiotherapy more effective when given during/ shortly prior to radiation delivery

E.g cisplatin, temozolamide

Question 8

What is radical radiotherapy?

Answer 8

When radiotherapy used to treat cancer as part of a curative strategy.

May be used in different settings:
Neoadjuvant- before
Adjuvant - after
Definitive

Question 9

What is the role of neoadjuvant radical radiotherapy?

Answer 9

Tumour downsizing, facilitating clear surgical resection margins
Reduce post op regional recurrence rate
Theoretically reduce rate of distant metastasis

Question 10

What can neoadjuvant radiotherapy be given with?

Answer 10

Simultaneous chemotherapy to increase efficacy

= chemoradiation
Side effect profile more severe, so patients need to be suitably fit

Question 11

Give some examples where chemoradiotherapy is used

Answer 11

Oesophageal cancer

Rectal cancer

Question 12

When is adjuvant radiotherapy given?

Answer 12

In situations where risk of locoregional cancer recurrence after definitive surgery is considerable due to:
Positive or close surgical margins
Involved lymph nodes
High grade tumour

Question 13

Give examples of when adjuvant radiotherapy is used

Answer 13

Breast cancer
Endometrial cancer
Cervical cancer
Head and neck cancers

Question 14

What can adjuvant radiotherapy be combined with?

Answer 14

Chemotherapy

Question 15

In breast cancer after WLE, adjuvant radiotherapy has been show to reduce locoregional recurrence by…

Answer 15

50%

Question 16

The combination of WLE and adjuvant radiotherapy has equal efficacy to…

Answer 16

A mastectomy with respect to long term local control rates

Question 17

There are some cancers that can be cured by chemoradiation alone, without need for surgical input, for example…

Answer 17

Head and neck
Cervical 
Bladder
Anal 
Prostate - can be cured with radical RT in addition to hormone treatment (LHRH agonists)

Question 18

What is palliative radiotherapy given for?

Answer 18

Symptom control

Usually in 1,5,10 fractions as opposed to radical RT given between 20-37 fractions

Question 19

What are some examples of indications for palliative RT?

Answer 19

Tumour related bleeding, pain or other pressure related sequelae - MSCC, SVCO

Question 20

Why after palliative RT might symptoms temporarily worsen?

Answer 20

Due to the oedema caused from the tissue destruction

Question 21

How long can it take for symptom relief to occur after palliative RT?

Answer 21

Can take 4-6 weeks

Question 22

What is radiotherapy dermatitis?

Answer 22

Side effect of external beam ionising radiation.
Confined to area of skin irradiated, skin changes are sharply demarcated
Can be acute or chronic

On examination:
Erythema
Desquamation (peeling)
If severe: necrosis and ulceration

Question 23

What are some short term side effects?

Answer 23

Depends on area treated
Erythema
Lymphoedema 
Nausea and vomiting (more likely if treatment near stomach or brain) 
Hair loss (only in treated area) 
Dysphagia, sore throat, mucositis 
Low blood counts if bone marrow affected
Diarrhoea 
Dysuria 
Sterility

Question 24

What late side effects can occur?

Answer 24

Skin - pigmentation, telangiectasia 
Bone - fractures, impaired growth
Eyes - cataracts
Lungs - fibrosis
Heart - cardiomyopathy 
Bowel - strictures, adhesions, fistulas 
Gonads - infertility, early menopause