Radiotherapy in Symptom Management Flashcards
Radiation : MOA
- ionizing radiation damages DNA
- Xrays or linear accelerator
- gamma rays from radioactive source
- Direct damage to DNA:
- base deletions, breaks
- Indirect damage:
- toxic free radicals from interaction of radiation and water
- damage to endothelial cells
- apoptosis
Radical Radiotherapy
- cure
- minimizing long term damage to normal tissue
- radiation dose is built up with daily treatment over several weeks
- can accelerate or hyperfractionate
- 6-8 weeks in duration
Palliative Radiotherapy
- aim is control of symptoms with minimal acute radiation reaction
- majority of tumour cells killed (60-80%) in first 1-2 doses
- short courses, low doses = less acute reaction
- minimizes late damage to normal tissues
Radiation treatment planning
- Immobilization:
- face masks, etc
- Treatment volume dosing
- CT sim
- Dosimetric planning
- Verification
Types of radiation therapy
-
External beam radiation (electrons)
- Xrays
- linear accelerator
-
Brachytherapy
- radiactive sources placed directly onto or into treatment area
- iridium, cobalt
-
Systemic radioisotopes
- target specific tissue or pathophysiology
- radioiodine for thyroid cancer
- strontium for bone mets
Acute side effects of radiation (during treatment - several weeks)
- from loss of epithelial cells
- skin erythema, desquamation
- mucositis
- esopahgitis
- non infectious cystitis
- GI irritation
- skin infection
- usually recovers in weeks
Late side effects of radiation
- Vascular damage, tissue ischemia
- Skin
- atrophy, fibrosis
- telangectasias, necrosis
- GI tract
- stricture
- bleeding, telangectasias
- perforation
- malabsorption
- enteritis, colitis, proctitis
- Bladder
- bleeding
- strictures
- fistulae
- Oral cavity:
- mucosal atrophy
- bleeding
- caries
- mandibular necrosis
- Lung:
- fibrosis
- Eye:
- cataract, dry eye
Management of radiation side effects: SKIN
- desquamation rare in palliative doses
- do not use talcum, gentian violet –> metallic salts increase skin reaction
Management of radiation side effects : MUCOSITIS
- chlorhexidine mouthwash
- anticandidals
- NG feeds
- oral hygiene and dental assessment for curative intent radiation
- avoid alcohol and smoking
Management of other radiation side effects
- Pneumonitis : steroids and antibiotics
- GI : nausea management
- Cystitis : analgesics, rule out infection, flomax, buscopan
Radiotherapy and symptom control : general indications
- Pain
- Bone
- visceral
- Neuropathic
- Local pressure
- SCC
- Cranial nerve palsies
- Obstruction
- Bronchus
- Esophagus
- SVC
- Hydrocephalus
- limb swelling
- Bleeding
- hemoptysis
- hematuria
- vaginal bleeding
- rectal bleeding
Radiation for bone pain
- bone pain
- pressure on nerves
- pathological fracture
- Effective within days to weeks, durable response of months-years
- Can re-treat with good response
- Single fraction :
- more pain flares
- higher rate of retreatment
- Multiple fractions:
- to treat path fracture
- spinal cord compression
Wide field treatment for bony mets
- multiple sites of disease and pain
- diffuse
- Wide field RT: up to half the body at a time
- Greater toxicity: GI, bone marrow suppression, fatigue, pneumonitis
Radioactive isotopes for bony pain
- isotopes concentrate at bone met sites
- focal release of beta particles, gamma release
- Strontium-89
- Samarium
- as effective as EBRT, fewer side effects
- AE : thrombocytopenia, neutropenia
- analgesia onset - MONTHS
- Expensive
- renal excretion, must be continent of urine to prevent contamination
Indications:
- multiple painful bony mets
- local radiation not feasible
How does radiation acheive pain control?
- not clear
- tumour shrinkage may not occur
- osteoclast activation?
Pain flare after radiation
- first few days
- 1-2 days duration
- dexamethasone
- opioids
Radiation for pathological fracture
- if surgery not indicated or possible
- Post operative internal fixation
- prevents progression
- if widespread disease, limited prognosis, good pain control –> no RT
Radiation for SCC
- Dexamethasone 4 mg qid
- Lymphoma and SCLC - primary treatment is chemo
- Surgery first if:
- good PPS
- solitary mets
- single level cord compression
- extensive vertebral collapse into spinal canal
- Radiation post op
- primary radiotherapy is surgery not indicated or wanted
Radiation for Brain mets
- Dexamethasone 4-8 mg daily
- Solitary brain met - surgery or SBRT and post op RT
- WBRT for mutiple diffuse mets
- palliation of headache, motor and sensory loss, confusin in 80%
- median survival < 6 months
- brain mets = widespread advanced disease
- Need careful patient selection and discussion of goals of care
Acute toxicity WBRT : alopecia x2-3 months
Long term toxicity WBRT : neurocog impairment
Meningeal carcinomatosis and RT
- Pre terminal event
- survival few weeks if untreated
- multifocal radiculopathy, cranial neuropathy, headache, backache
- raised ICP
- breast, lung, leukemia, lymphoma
- WBRT and whole spinal RT extends prognosis from weeks to maybe short months, all taken up with treatment
- Skull case for CN or spinal cord nerve roots for sx control may be indicated
Brain mets RT decision algorithm
-
Good PPS
-
multiple mets
- WBRT
-
solitary /oligomet
- surgical?
- non surgical - radiosurgery, WBRT
-
lymphoma, SCLC, germ cell tumour
- chemotherapy
-
multiple mets
-
Poor PPS
- supportive care
Other neurological symptoms that may benefit from Radiation
- Cranial nerve palsies - skull base effective
- Peripheral nerves - lumbosacral nerve roots, apical lung tumours, brachial pleus, lymph nodes
- Choroidal and orbital mets
- Cerebral lymphoma - HIV, WBRT role in question
Obstructive symptoms : SVCO
- Occlusion by external compression
- intraluminal thrombosis
- direct invasion of vessel
- Lung cancer, lymphoma
- Presentation:
- headaches
- somnolence
- dizziness
- edema
- dysphagia
- dyspnea
- cough
- hoarseness
- engorgement and dilation of facial veins
- facial edema
SVCO management general
- steroidse
- SVC stent
- Chemo for SCLC germ cell, lymphoma
- Radiotherapy