Approach to the cancer case 1 + 2 Flashcards
What is cancer?
An uncontrolled proliferation of abnormal cells
What proportion of dog/cats will develop cancer in their lifetime?
1 in 4 dogs
1 in 6 cats
Will develop a malignant tumour during their lifetime
For what reasons do patients die of cancer?
- Delayed / erroneous diagnosis
- Failing to treat properly: Primary disease, Metastatic spread
- Ineffective treatment
- Owner decides not to treat
List the main oncology principles to be aware of as a vet
- Cancers do not go away
- Know what you are treating
- Work to understand owner goals
- Treat early for best chance of cure
- Plan treatment well
List the basic diagnostics available for cancer cases
- History
- Physical examination
- Minimum database (CBC, Biochem, UA) - Usually for assessment of co-morbidities, some px markers
- Biopsy
- Cytology
- Histology - Grading - Imaging
List some advanced diagnostic tools available for cancer cases
- Immunochemistry: cytochemistry and histochemistry
- Flow cytometry
- PCR
- Electrophoresis
List the 10 AVMAs signs of cancer
- Abnormal swelling that persists or continues to grow
- Sores that do not heal
- Unexplained weight loss
- Loss of appetite
- Bleeding or discharge from a body opening
- Bad odour, especially from the mouth
- Difficulty eating or swallowing
- Reluctance to exercise
- Difficulty breathing, urinating or defecating
- Change in behaviour
What information would you gather on the history of an animal with suspected cancer?
- General - Diet, travel, medications
- When was it noticed?
- Behavioural information
- Size
- Growth rate?
- Changes in appearance?
- Any other masses? - Other clinical signs / co-morbidities?
- Changes e.g. pu/pd, swollen limbs, petechaie, pale gums, swelling or ecchymoses
Describe the steps involved in a lesion examination
- Measure and record size and location of all lesions
- Assess invasiveness and attachment to underlying tissues (Feeling of mass not a good indicator of lesion type)
- Look for characteristics associated with malignancy
- Pain: skin tumours rarely painful cf inflammatory lesions
Describe the steps involved in a general physical examination
- General condition and BCS assessment
- Palpation over the whole body for other lesions.
- Palpation of lymph nodes especially draining nodes
- Palpation looking for signs of pain, especially over bones and spine.
- Oral and rectal examination
- Assessment of CVS and respiratory systems.
- Abdominal palpation
- Mentation and neuro assessment
Haematology can only be used to diagnose which cancer?
Leukaemia
Haematology is required before which treatment is given?
Chemotherapy
Can biochemistry be used to diagnose cancer?
No
- Poorly sensitive to organ infiltration
- Paraneoplastic syndromes
- Concurrent disease
Cytology samples are obtained using?
FNAs
Histopathology samples are obtained using?
Tissue biopsys
Before treatment what should all cancer patients have?
A pre-treatment diagnosis
List the main features of cytology and its benefits
- Relatively non-invasive
- Often requires minimal restraint
- Minimal tissue disruption
- Rapidly performed
- Rapid results
- Cheaper
Which features of cytology are not useful?
- No architectural detail
- Small numbers of cells examined - ?representative
- Limited assessment of tumour type/grade
What are the benefits of histopathology?
Architecture apparent
Larger sample size = More representative
More accurate tumour type/grade
What are the disadvantages of using histopathology?
More invasive
GA (or sedation) required
Moderate tissue disruption
More time consuming
Delay in results
More expensive
When might FNA and biopsy be useful?
Examples include: tumours requiring high morbidity surgery or when cytology result does not align with clinical picture
What are the main considerations when performing an FNA
Do not go through the lesion (seeding)
1 cc of negative pressure is enough
Be vigorous sampling in multiple directions
Cover needle hub as you withdraw.
In which tumours/tissues is it best to use the needle off FNA approach?
Lymph nodes
Suspected round cell tumours
Describe how to correctly make spears once you have an FNA sample
- Use 5ml of air to rapidly expel the sample
- Slide must be clean
- Use weight of the slide to spread the sample
- Smear without excessive downward pressure
- Stain slide with less material and check there are intact cells (before dog is woken up if sedated/GA)
- Label with penicl
In which situations is an FNA contra-indicated?
- Bleeding
- Risk of pneumothorax, urine or abscess leaking after sampling
- Tumour transplantation deeper into tissue: care not to go through lesion
If a patient is bleeding, when may if be ok to perform an FNA?
If platelet count normal and no evidence of coagulopathy then usually OK
Monitor patients afterwards
FNA is best for tumors with which characteristic?
Better for tumours which don’t exfoliate well but risk of cell damage
Describe when an impression smear/brush is indicated?
Intra-op or post-mortem samples
Ulcerated superficial lesions
Nasal biopsies
Airway lesions
Describe the impression smear technique
- Collect sample
- Blot surface: remove debris if ulcerated lesion, remove blood
- Dab against slide - make multiple spots
What are some problems with using FNA
- Non-diagnostic samples (around 20%): always check before sending away
- Non-representative samples
List the 5 different tissue biopsy techniques
Needle core biopsy
Incisional biopsy
Surface and pinch biopsies
Punch biopsy
Excisional biopsy
What are the risks of biopsy?
- Haemorrhage
- Transplantation of tumour cells
- Compromise future surgery
- Damage to adjacent structures
What is a needle core biopsy?
Cylinder of tissue is removed from the lesion by a specialised needle
Describe the two needle types available for needle core biopsies
- Trucut needles
- Two handed operation
- Need assistance
- Can be cold sterilised - Cook’s/Arnolds Biopsy Needles
- Semi automated
- Can be cold sterilised
What are the advantages of a needle core biopsy?
- Larger sample than aspirate -> some evaluation of architecture
- Comparatively inaccessible tissues can be accessed percutaneously
- Multiple samples can easily be taken
- Superficial lesions can be biopsied under sedation and local anaesthesia
What are the disadvantages of a needle core biopsy?
- Small samples size compared to other biopsy - might not be sufficient to view architectural change
- Greater risk of complications compared to FNA - esp for intracavitatory biopsies
- NOT GOOD FOR LYMPH NODES
- Insensitive to metastatic disease
- Inadequate for architectural assessment in lymphoma
Describe the procedure for a needle core biopsy
- Adequate restraint
- Clip, prepare site aseptically
- Make small stab incision in skin (essential or will blunt needle)
- Immobilise mass and introduce needle (ultrasound guided very useful)
- Once embedded in tissue..
- Advance central obturator, do not go through far border of lesion
- Rotate through 90o
- Briskly advance outer cannula over central obturator
- Remove from mass
- Retract outer cannula
- Handle biopsy with care
When biopsying which tissues is ultrasound guidance most useful?
Hepatic biopsy
Renal biopsy
- Need to be careful
- Needle parallel to medulla
- Not without risk
Thoracic mass
A jamshidi needle is used for which biopsy type?
Bone core biopsy
What must you be careful not to do when performing a bone core biopsy?
Do not penetrate far cortex
Risk of pathological fracture
What is an incisional biopsy?
Surgical removal of a segment of solid tissue
Which type of incisional biopsy is used most commonly?
Wedge biopsy
- inverted wedge allows easy closure
What are the advantages of an incisional biopsy?
- Good evaluation of architecture
- Histopathological grading
- Surgical approach allows selection of biopsy site
- More tissue: can carry out special stains etc
What are the disadvantages of an incisional biopsy?
GA normally required
Increased time
Both increase costs
What are the main considerations when performing an incisional biopsy?
- Plan your site
- Avoid major structures
- Avoid necrotic, haemorrhagic or infected areas
- Position incision and biopsy so that entire biopsy tract can be removed during subsequent surgery
- Make the incision large enough to harvest the sample without excessive tissue manipulation
- Include a portion of normal tissue only if easy to do so
Surface pinch and grab biopsies can be used for which tissues?
Accessible surfaces:
- Respiratory tract
- Gastrointestinal tract
- Urogenital tract
Describe how you would use the surface pinch and grab biopsy technique for nasal tumours
Measure distance to insert grabs from radiograph
Do not insert further than medial canthus
For cats use cut-off urinary catheter and aspiration
When can punch biopsies be used?
Cutaneous and other superficial lesions only
NOT for lymph nodes
How should a punch biopsy be carried out?
Sedation (+/- local)
Rotate punch continuously in SAME direction so don’t shear layers apart
What is an excisional biopsy?
(Attempted) surgical extirpation of a lesion or mass, followed by removal of biopsies from it for histopathological evaluation or submission of whole sample if possible
In which 3 exceptions can excisional biopsies be performed without a pre-treatment diagnosis?
Haemorrhaging splenic masses
Mammary tumours
Pulmonary tumours
What must be done before an excisional biospy?
Staging of the tumour
Excisional biopsies are widely used to treat which tumours?
Skin tumours
List the contraindications for excisional biopsy for skin and s/c masses
- Rapidly growing mass
- Ill-defined or poorly demarcated lesion
- Peritumoural oedema or erythema
- Skin ulceration
- Injection site masses in cats
- FNA suspicious for MCT or STS
- Non-diagnostic FNA
What should happen to all excised excisional biopsies?
Submitted for histopathological evaluation - only way to assess adequacy of excision
Once cancer has been diagnosed in a patient what are the next steps to consider?
Client communication
Active monitoring
Staging
Tumour related complications
Comorbidities and general health
What are some general tips when communicating with clients after a cancer diagnosis
- Clients often find a diagnosis of cancer very distressing
- May remember only a minority of the information you give them
- Some clients benefit from having time to come to terms with the diagnosis
- The client may need more time than you can give them in the middle of a busy surgery
- Explains the knowns and unknowns clearly
- Be clear if the disease is likely to be fatal but dont prognosticate too early
What are some common unknowns after a cancer diagnosis
- Sometimes exact type
- Stage
- Co-morbidities
- Owners willingness to treat
- Uncertainty about outcomes of treatment
What is clinical staging?
Process by which we assess the extent of the disease
Describe the 3 clinical stages of solid tumours
T = primary tumour
N = metastatic disease in local and regional lymph nodes
M = Distant metastatic disease
How can you clinically stage a T lesion
- Clinical exam
- Location and palpable extent
- Fixation: to deep tissues, to skin
- Ulceration
- Imaging
- Direct visualisation
Describe how you can stage T tumours using imaging in first opinion practice
- Plain films
- Contrast radiography: urogenital, GI and CNS tumours
- Ultrasonography: abdominal masses, parenchymatous organs
What % of mineral content of bone must be lost for lysis to become apparent on plain radiography?
More than 60%
How can stage T tumours be diagnosed using direct visualisation
Endoscopy
- Gastrointestinal tract
- Urogenital tract
- Respiratory tract
Laparoscopy
Thoracoscopy
Exploratory surgery
What is the use of CT scanning for stage T lesions
Great for bony lesions
Radiation planning
What is the use of MRI scanning for stage T lesions
Best for CNS lesions
Many more shades of grey in soft tissue compared to radiography
Tumour metastasis is divided into which two broad categories?
Haematogenous
Lymphatic
Describe haematogenous metastasis
Dissemination via the circulatory system
Sarcomas
Malignant melanoma
Describe lymphatic metastasis
Dissemination via the lymphatic system
Local and regional lymph node spread
Mast cell tumours
Carcinomas
Malignant melanomas
Can imaging alone be used to diagnose neoplasia?
No
Need Biopsy and histopathology OR suitable sampling and cytology
Describe how you can clinically stage N lesions
Palpation
Imaging
Cytology/histology
Imaging
FNA
Biopsy
Describe palpation for stage N lesions
Relatively insensitive to metastatic disease
Any palpable abnormalities
- Size
- Texture esp increased firmness
- Fixation
How can thoracic radiography be used for stage N lesions
Moderate to marked enlargement of nodes detectable
- Lateral thorax: Suprasternal, cranial mediastinal, tracheobronchial
- DV thorax: Increases sensitivity
How can abdominal radiography be used for stage N lesions
Medial iliac (sublumbar) lymph node enlargement
Very unlikely to detect enlargement of mesenteric nodes unless massively enlarged
How can ultrasound be used for stage N lesions
Esp useful for subtle enlargement of the iliac (sublumbar) and mesenteric lymph nodes
What is Lymphangiography?
The use of imaging, such as X-ray or MRI , to visualize the body’s lymphatic system.
How is Lymphangiography used to stage N lesions
- Detection of sentinel nodes
- Inject contrast into the tumour to find out which nodes drain it
- Does not tell you if they are affected by metastases
- Only tells you which are draining nodes
How are FNAs used to stage N lesions
More sensitive than palpation or needle core biopsy
Not infallible
- Can have –ve aspirate from +ve node
- Use needle only technique
Describe biopsying lymph nodes to stage N lesions
Lymph node excision best
Trucuts are poor
Describe the main features of lymph node metastasis
- Most tumours which spread by the lymphatic route go to the nearest node towards the centre of the body i.e. towards thoracic duct
- Normal lymph nodes act as a barrier to tumour spread
- Once node is grossly affected by metastatic disease probably contributes little to defence against metastasis
A cranial abdominal tumour is most likely to metastasise to which LN?
Sternal lymph nodes
A thyroid carcinoma is most likely to metastasise to which LN?
Retropharyngeal
List the common sites of stage M lesions
Lung
Parenchymatous organs e.g. Liver, spleen, kidney
Bone
Skin
CNS
Distant nodes
How can a clinical exam be used in diagnosing stage M lesions
Skin mets may be obvious
Pulmonary metastatic disease is very difficult to pick up on examination
- History helps
- Adventitious sounds uncommon
- May pick up if concurrent effusion
Cough is uncommon
How is clinical pathology used in staging M lesions
Organ dysfunction secondary to metastatic invasion
Not terribly sensitive or specific
How is advanced imaging used for stage M lesions
More imaging leads to increased lesion identification
How are most stage M lesions diagnosed?
Inflated Xrays x 3 views +/- ultrasound good enough for the majority of cases
How can metastasis to parenchymatous organs be diagnosed?
Ultrasound generally superior to radiography
In older dogs, which conditions can be mistaken for metastatic spread to parenchymatous organs? How can you confirm?
- Nodular hyperplasia in the liver
- Nodular hyperplasia, lymphoid hyperplasia, haematomas in the spleen
- Confirm by FNA
List the limitations of the TNM system?
- Animals do not always present with the primary disease
- Metastatic disease: Bony mets, LN mets in tonsillar carcinoma
- Paraneoplastic syndromes
- Biological behaviour of the tumour must be in mind: some very aggressive tumours are always at a more advanced stage than is clinically detectable
When should cancer cases be referred?
Most oncology cases can be managed well in general practice.
Referral for:
- Specialist expertise
- Advanced treatments
- Odd tumours / uncertain diagnoses
- Tricky clients
- More aggressive tumours
List some examples of highly metastatic tumours
- Oral/mucosal malignant melanoma
- Haemangiosarcoma
- Appendicular osteosarcoma (dog)
- High grade MCTs
- Subungual malignant melanoma (dog)
- Poorly differentiated mammary tumours (dog)
- Most mammary carcinomas in cats
Name some tumours with a low metastatic potential
- Oral fibrosarcoma
- Non-tonsillar oral squamous cell carcinoma
- Most ST sarcomas
- Sebaceous adenocarcinoma
- Low grade MCTs
- Multilobular osteoma /osteosarcoma of bone
- Intranasal tumours
List some tumours which don’t metastasise
- Oral acanthomatous ameloblastomas: Aka basal cell carcinomas or acanthomatous epulids
- Haemangiopericytoma
- Schwannoma/neurofibroma
- BENIGN TUMOURS
