radiation oncology Flashcards
how many canadians will develop cancer
2 in 5
how many canadians will die of cancer
1 in 4
what are the 5 most common cancers
lung breast colorectal prostate skin
what is a tumor/neoplasm
unregulated cell growth that is UNable to invade the basement membrane and travel to/metastasize to other structures
abnormal mass of tissue that results when cells divide more than they should or do not die when they should
may be benign or malignant
what is cancer
abnormal division with the ability to invade/metastasize
term used for diseases in which abnormal cells divide without control and are able to invade other tissues
what are the 4 hallmarks of cancer
- inappropriate cell proliferation
- -increased cell production
- -decreased cell death - neoangiogenesis
- invasion and metastasis
- genomic instability (predisposition to mutation)
- -receptors can change, they are error prone and in tumours can have trouble repairing properly
how does cancer spread
- direct invasion
- lymphatics
- hematogenous via the bloodstream
- transcoelomic (pleural, pericardial, peritoneal)
how is cancer staged
TNM
- Tumor–> size and/or extent of the primary tumor, correlates with direct invasion
- nodes–> whether there has been spread to nearby lymph nodes, correlates with lymphatic spread
- metastasis–> spread to other parts of body, correlates with hematogenous spread
why does staging matter
udnerstanding tumor spread can help us to
- conduct a proper history (about location, spread etc) and physical exam
- order the correct staging investigations
why do we stage cancers
- common language of communication for health care providers to describe the extent or severity of cancer
- guides treatment
- estimates prognosis
- allows us to compare results over time
- provides a clinical trial standardization
stage does stage 0 cancer indicate
carcinoma in situ
what does stage I, II, III cancer indicate
higher numbers indicate more extensive disease…
larger tumor…
extension into adjacent tissues…
spread to nearby lymph nodes
what does stage IV cancer indicate
metastasis to distant sites
what are the types of staging
- clinical staging
- -physical exam
- -imaging
- -lab tests - pathological testing
- -pathology reports
- -surgical reports
what does the “Stage” of a cancer indicate
tumor extent, node status, spread/severity
what is the “grade” of a cancer indicate
describes how normal/abnormal the cells look/appear in pathology and their level of differentiation compared to their precursors
what are the goals of cancer treatment
- radical
- -curative intent
- -complete ablation - adjuvant
- -curative-intent
- -addresses microscopic disease
- -reduces recurrence risk - palliative
reduce or prevetn sx
what types of things should you consider when designing cancer therapy
patient factors
tumor factors
treatment factors
examples of patient factors
performance status
what can the patient tolerate medically and surgically (can they life flat for radiation therapy)
co morbidities
past surgeries
patient preference
examples of tumor factors
type of cancer (histology, natural history, etc)
characteristics and extent of cancer (stage TNM, size, location, invasion etc)
symptoms
is complete resection/oblation possible
what are some treatment factors
availability and effectiveness of treatment
potential toxicity
what is the mainstay of radial therapy for solid cancers
surgery
what is the mainstay of radial therapy for hematollgic cancers
chemo
what are your cancer treatment options
surgery
radiation
chemo
how is radiation therapy used to manage cancer
it radical/curative therapy for some solid cancers (with or without chemo)
primarily used for HEENT cancers, lung cancers and skin cancers
how does radiation therapy work
it is high energy ionizing photons (“strong xrays”) that cause damage to cellular DNA
cancer cells have difficulty repairing cell damage compared to normal tissues
treatment is usually delivered in a series of small daily treatments called FRACTIONS
why do you give radiation in small doses/fractions
allows time for normal tissues to heal
how do you calculate total radiation dose
number of fractions x daily dose equals total dose
what are the 4 types of radiation therapy
- enteral beam radiation therapy (EBRT)–most common
- brachytherapy
- isotope therapy
- radio-immunotherapy
how does enteral beam radiation therapy (EBRT) work
radiation given from a source outside of the body (“that big spinny thang”)
most treatment is delivered by external beams which must go through normal tissue to reach the target cancer–> radiation side effects are dictated by the area the beams traverse
creates free radicals which attach to broken DNA so they cant be repaired
how does brachytherapy work
direct application of a radioactive source into/adjacent to the tumour
use in cervix, prostate, lung, esophagus
how does isotope therapy work
IV or oral ingestion of radioactive isotopes that concentrate in malignant tissue
do all tumours have the same radiosensitivity
no
which tumours are highly radiosensitive
lymphoma
leukemia
seminoma
which tumours are medium radiosensitive
squamous cell cancers–
skin
oropharynx
bladder
cervix
which tumors have low radiosensitivity
renal cancer
osteosarcoma
what are acute side effects from radiation toxicity
those that occur within 6 months of treatment usually due to acute inflammatory reaction
i.e skin desquamation following chest wall irradiation, fatigue
what are late side effects from radiation toxiciy
generally those occurring after 6 months, usually due to fibrosis of connective tissue and obliteration of small blood vessels
i.e changes in skin pigmentation, fibrosis and telangiectasia
what is the framework for approaching cancer cases
- diagnosis
- staging and spread
- management reasoning
- -patient, tumour, treatment factors
- -radiation therapy side effects
treatment for breast cancer
surgical treatment with partial or radical total mastectomy
followed by radiation therapy
post radiation therapy with tamoxifen if estrogen receptor positive
treatment for non small cell carcinoma of the lung
surgical lobectomy
then radiation for spread to nodes with chemo
treatment for prostate adenocarcinoma
surgical radical prostatectomy then radiotherapy with external beam or brachytherapy (especially if positive margins)
hormonal therapy with an LHRH antagonist to reduce testosterone
acute side effects of pelvic radiation
bladder irradiation (frequenct, urgency, dysuria)
bowel irritation
ED
fatigue
late side effects of pelvic radiation
chronic bowel or bladder changes
rectal bleeding
uretheral stricture
SBO
acute side effects of thorax radiation
esophagitis
worsening SOB/cough
fatigue
late side effects for thorax radiation
pneumonitis
esophageal stricture
rib damage
cardiac damage
2nd malignancy
how can you best image the liver
well done by U/S
what part of the body is particularly suscueptible to radiation
mucous membranes
what is the key to cancer history and physical
pain, soreness, swelling etc
symptoms of mets–> local, lymphatic, hematogenous spread
define radiation oncology emergency
medical condition arising from a reversible threat to organ function requiring radiation treatment within a few hours of diagnosis
define spinal cord compression
compression of the dural sac and its contents (spinal cord, cauda equina or both) by an extradural tumour mass
what is the minimum radiologic evidence for cord compression
indentation of the thecal/dural sac at the level of the clinical features
what % of cancer patients have spinal mets
40%
what % of patients with spinal mets develop symptomatic spinal cord compression
20%
where do we most often see spinal mets
60% in thoracic spine because biggest
30% lumbosacral spine
10% cervical spine
what is the pathophysiology of spinal cord compression
growth and expansion of the bone met into the epidural space or neural foramina extension by para-spinal mass–> causes destruction of vertebrae and collapse and displacement of bony fragments into the epidural space
damage mainly VASCULAR–> increased arteriole pressure, venous plexus compression, reduced capillary blood flow
leads to spinal cord edema
result is white matter ischemia and infarction and permanent cord damage
what is the first symptoms of spinal cord compression in 90% of patients
back pain
pain is hallmark of spinal cord compression
what is the most common symptom of spinal cord compression to cause people to seek medical attention
weakness
sphincter dysfunction of bladder and bowel can happen but almost always WITH the other sx
describe the sensory symptoms of spinal cord compression
pain is most common, often preceeds other neuro deficits by months
often localized, most severe over the involved vertebrae (tightness sensation)
can be radicular around the trunk or down a limb
can have numbness, paresthesia
motor symptoms of spinal cord compression
depends whether UMN or LMN lesion
above L1/L2 is spinal cord compression, below that it is cauda equina
are the following present or absent in a UMN lesion?
- weakness
- atrophy
- fasciculations
- reflexes
- tone
- yes
- no
- no
- increased
- increased
are the following present or absent in a LMN lesion?
- weakness
- atrophy
- fasciculations
- reflexes
- tone
- yes
- yes
- yes
- decreased
- decreased
what investigations should you do for spinal cord compression
plain x rays
CT is reasonable to start
MRI–test of choice when suspicion is high –> myelography if MRI not available
consult rad onc/neurosurgery
good spinal cord compression prognostic factors
ABLE TO WALK
tumor type responsive to chemo/radiation
gradual onset of symptoms with slow progression
good general health
vertebreal body intact
poor spinal cord compression prognostic factors
unable to walk
tumor type resistant to chemo/radiation
acute onset with rapid progression
poor general health
vetebral body collapse
treatment for spinal cord compression
- analgesics
- STEROIDS ARE FIRST LINE–> DECADRON
- surgery–> helps with tissue diagnosis//given prior to radiation to improve outcomes in certain patients//can help with vertebral body instability and other functional stability//wound healing and rehab post op may not be suitable for all patients
- radiotherapy–> offered to all patients who are NOT candidates for decompressive surgery upfront, if they are surgical candidates you give radiation afterwards // give 5-10 fractions directed to involved site//goals are to improve pain and improve/maintain ambulation
- chemotherapy–> may be useful in select cases of highly chemosensitive tumours but generally not first lime
what is the first step in spinal cord compression treatment
steroids–> DECADRON
steroids help retain motor function
who gets surgery for spinal cord compression
spinal instability
bony compression
patients with no/remote cancer diagnosis
neuro progression
who gets radiotherapy for spinal cord compression
medically inoperable
ambulatory
diffuse disease
what should be considered when deciding how to treat spinal cord compression
medical status
ambulatory status
structural factors
anticipated outcome
treatment goals
what % of patients with lung cancer will develop superior vena cava obstruction
2-4% at some point–more commonly from small cell lung cancer than non small cell because of more rapid growth
what causes superior vena cava obstruction in lung cancer?
invasion
external compression
internal blockage
can be due to…
- -benign causes–> thrombus, aneurysm, goitre, etc
- -malignant–> lung cancer (75%), lymphoma, germ cell tumour, thyroid cancer, mets
what cancers are associated with superior vena cava obstruction
lung (75%)
lymphoma
germ cell tumour
thyroid cancer
mets
symptoms of superior vena cava obstruction
3Ds
dyspnea/laboured breathing
distension (edema of face/arms, may have erythema)
dilated chest wall vessels
investigations for superior vena cava obstruction
CXR
CT with contrast to see the SVC
treatment for superior vena cava obstruction
- ABCs with supportive therapy
- steroids (dex)
- radiotherapy–best for non small cell lung cancer//wait for tissue confirmation unless patient is very unwell//takes DAYS TO WEEKS to work//relief of symptoms is the major effect in most cases
- chemo–> best for small cell lung cancer and lymphoma
- surgery–> endovascular stent for rapid relief
what provides rapid relief from superior vena cava obstruction
endovascular stenting surgery
what is the biggest problem with brain mets
increased ICP
what are the 3 rad onc emergencies we could see
superior vena cava obstruction
brain mets
spinal cord compression
malignant hemorrhage
how do brain mets present
widely variable
can be symptomatic
- -headache
- -cognitive impairment
- -hemoparesis
- -seizures
- -change in vision or hearing
- -LOC
or can be asymptomatic
treatment for brain mets
- ABCs and supportive therapy
- medical management with steroids –> dex with or without antiepileptics
- surgery–> reduce mass effect, diagnosis, improve outcomes
- radiation–> goal is symptoms improvement but this can take time and can cause WORSENING EDEMA initially
what causes malignant hemorrhage
due to disruption of friable vasculature associated with the tumour
most commonly in gyne/cervix, lung and head and neck cancers
treatment of malignant hemorrhage
- ABCs and supportive management
- physical measures–> packing, cautery, surgery
- vascular embolization
- radiation–though results are not immediate–can take days to weeks to work
