radiotherapy

Question 1

mechanism of radiotherapy

Answer 1

X rays cause ionisation events
Ion radical disrupt bonds in the DNA helix
Pathognomonic damage is the DNA double strand break

Question 2

DNA damage and pathways

Answer 2

Question 3

radiotherapy

Answer 3

DNA repair takes about 6 hours
Normal tissue will therefore recover between small daily fractions

Question 4

fractionation schedules

Answer 4

Conventional (1#/d, 5 d/week) 60 Gy in 30 fractions over 6 weeks 2Gy/#
Hypofractionation (higher dose / #) 55 Gy in 20 fractions over 4 weeks 2.75Gy/#
Accelerated (>1 dose per day) 70Gy in 35fractions over 6 weeks 2 Gy/#
Hyperfractionated Accelerated RT (CHART) 54 Gy in 36 fractions over 12 days 1.5Gy/# increased 2 yr survival in NSCLC 10% - 20%

Question 5

acute effects of radiotherapy

Answer 5

Acute
Tiredness
Mucositis
Skin reaction
Alopecia
Myelosuppression
Nausea
Anorexia

Question 6

chronic efects of radiotherapy

Answer 6

Chronic
Sterility
Cataract
Intestinal stricture
Pulmonary fibrosis
Nephritis

Hepatitis
Myelitis

Question 7

normal treatment volumes

Answer 7

Question 8

palliative radiotherapy

Answer 8

To relieve symptoms
Pain from bone metastatses
Pain from tissue infiltration/nerve compression
Spinal cord compression
Vascular compression - SVCO, lymphoedema
Bleeding – haemoptysis, haematuria …
Simple, short, fast

Question 9

superior vena cava obstruction

Answer 9

causes

Mediastinal tumours
Lung cancer
NSCLC, SCLC
Lymphoma
Hodgkins
Non Hodgkins
Thymoma
Metastases

Treatment
Dexamethasone
Chemotherapy
Radiotherapy

Question 10

bone mets

Answer 10

RT Highly effective
One dose (8Gy) is usually sufficient
Localise with bone scan or plain X rays

Strontium-90
Bisphosphonates

Question 11

other uses of radiotherapy

Answer 11

Radioisotopes
Sr90, I131,
Radio-labelled targeting agents
MIBG, monoclonal Abs (e.g mabthera)
Brachytherapy
Cervical cancer Cs or Cobalt
Intraluminal for lung, oesophagus….
Interstitial – radium needles, Ir 192

Question 12

treatment of cervial cancer

Answer 12

Cervical cancer brachytherapy

Question 13

chemoradiotherapy

Answer 13

The combination of chemotherapy with radiotherapy
Radiosensitisation
Spatial co-operation
Risk of increased toxicity

Question 14

treatments for certain cancers

Answer 14

Cervical cancer cisplatin
Anal cancer 5FU, mitomycin
Lung cancer cisplatin
Oesophageal cancer 5FU, cisplatin
Rectal cancer 5FU
Glioma temozolomide
Head and neck cancer cisplatin,cetuximab