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Oncology > Radiotherapy > Flashcards

Radiotherapy Flashcards

1
Q

Can radiotherapy be a sole treatment modality?

A

Yes i.e. prostate cancer

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2
Q

Can radiotherapy be used throughout all cancer treatment?

A

Yes - it can be used neoadjuvantly, adjuvantly, in palliation, as a primary treatment, and in conjunction with chemotherapy

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3
Q

Explain the science behind radiotherapy

A

X-rays are high energy with a short wavelength.
They are delivered by a linear accelerator (LINAC).
X-rays produced secondary electrons and free radicals that cause DNA damage (to cancer and normal cells)
Normal cells can repair damage and survive, cancer cells cannot.

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4
Q

What is a radiation dose denoted by?

A

the unit Gray (Gy)

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5
Q

Describe a common radiotherapy schedule for a H&N cancer patient with curative intent

A

70Gy in 35 fractions over 7 weeks

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6
Q

Describe some factors that influence the level of tumour kill and toxicity of radiotherapy

A
  1. treatment issues - total dose, overall treatment time etc
  2. co-morbidities - diabetes, smoking
  3. Intrinsic radio-sensitivity of the tumour, tumour hypoxia, tumour re-population
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7
Q

Which tumours are radiosensitive?

A

Seminoma, Hodgkin’s

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8
Q

Which cancer is relatively radio-resistant even at high doses?

A

Glioblastoma multiform

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9
Q

What is chemotherapy called when given along side radiotherapy?

A

Concurrent chemotherapy

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10
Q

What are the advantages of using concurrent chemotherapy?

A
  1. Improves efficacy of the radiotherapy treatment without having to significantly increase the dose of radiotherapy
  2. Makes the cells more sensitive to radiation
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11
Q

What are the disadvantages to concurrent chemotherapy?

A

These regimens are associated with increased radiation-related side effects

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12
Q

What is the most common external beam radiotherapy in the Uk?

A

3D-conformal radiotherapy

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13
Q

What does 3D-conformal radiotherapy entail?

A

The patient has individually planned radiotherapy based on the 3D shape of their tumour
Needs to be in the same position - may need head mask or tattoos

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14
Q

How is the tumour target defined?

A

The gross tumour volume has a margin added for microscopic disease spread = clinical target volume
Another margin is added to allow for minor daily variations in patient and tumour position = planning target volume

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15
Q

What is the planning target volume?

A

The total area of tissue being irradiated - combines the clinical target volume, with another margin to allow for minor patient movement

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16
Q

What are side effects in radiotherapy related to?

A

The anatomical area being irradiated i.e. the thorax will not cause diarrhoea

17
Q

When do acute side effects occur?

A

Usually after 5-10 fractions

18
Q

Describe acute side effects

A

Tend to increase during treatment and peak in first few weeks
Generally reversible
Examples oral mucositis, diarrhea, skin reactions

19
Q

Describe late reactions

A

Develop 3 months after radiotherapy and sometimes years later
Often irreversible and worsen over time, difficult to treat, need MDT and sometimes surgery

20
Q

Examples of late side effects

A

Fibrosis, blood vessel damage, lung fibrosis, skin atrophy, infertility

21
Q

Who has the highest risk of developing a secondary malignancy due to radiotherapy?

A

Younger patients treated for a good prognosis cancer

22
Q

Can radiotherapy be given to pregnant women?

A

No - it is teratogenic (causes birth defects)

23
Q

What is brachytherapy?

A

A form of radiation where radiation sources are placed within or close to the tumour

24
Q

What are the advantages of brachytherapy?

A

allows delivery of a localised high radiation dose to a small tumour volume, increasing the chance of tumour control, whilst minimising the dose to surrounding normal tissue.

25
Q

What cancers are commonly treated by brachytherapy?

A

Prostate cancer, gynaecological cancers, oesophageal cancer and H&N

26
Q

What are the two main types of brachytherapy?

A

Intracavity - the radioactive material is placed inside a body cavity such as the uterus and cervix
Interstitial - where the material is put into target, such as the prostate

27
Q

What advice does a patient receiving brachytherapy need?

A

They are radioactive, having radioactive substances inside them - no sex etc.

28
Q

What is a radioisotope?

A

A radioisotope is an unstable form of a chemical element, which emits radiation when it decays and is another method of radiation delivery.

29
Q

What is the most commonly used form of radioactive iodine?

A

I-131

30
Q

What cancer is I-131 used in?

A

Thyroid cancer

31
Q

What happens after someone has had I-131?

A

They must remain in a lead lined room for 4 days or until the radiation they are emitting is low enough to not to provide risk to others

Oncology (12 decks)

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