Approach to the cancer cases Flashcards
What is cancer?
- An uncontrolled proliferation of abnormal cells
- Independent of the requirement for new cells
- Cellular differentiation is often impaired
Why do so many pets die of cancer?
- Delayed / erroneous diagnosis
- Failing to treat successfully
- – Primary disease
- – Metastatic spread
- Ineffective treatment
- Owner decides not to treat
What are principles of oncology?
- 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
- – Mismanagement of case in early stages can often jeopardise later treatment success
What are signs of cancer?
- Abnormal swelling that persists or cont. to grow
- Sores that do not heal
- Unexplained weight loss
- Loss of appetite
- Bleeding or discharge from any body opening
- Bad odor, especially from the mouth
- Difficulty eating or swallowing
- Reluctance to exercise or loss of stamina
- Difficulty breathing, urinating, defecating
- Change in behavior
What can be used to diagnose cancer?
- History
- Physical examination
- Minimum database (CBC, Biochem, UA)
- Biopsy =
- Cytology
- Histology - Grading
- Imaging
- Immunochemistry, PCR, elecrophoresis
What history should be noted?
- General - Diet, travel, medications
- When was it noticed?
- Behavioural information =
- Size
- Growth rate?
- Changes in appearance?
- Any other masses?
- Other clinical signs / co-morbidities?
What should be done on clinical exam?
*Measure and record size and location of all lesions
*Assess invasiveness and attachment to underlying tissues
*Look for characteristics associated with malignancy
*General condition and BCS assessment =
* - Mentation
* - Palpation over the whole body for other lesions.
* - Palpation of lymph nodes especially draining nodes
* - Abdominal palpation
* - Assessment of CVS and respiratory systems.
*Depending upon clinical signs =
* - Palpation looking for signs of pain, especially over bones and spine.
* - Oral and rectal examination as appropriate
* - Mentation and neuro assessment
What are the advantages / disadvantages of cytology?
–Relatively non-invasive
–Often only physical restraint
–Minimal tissue disruption
–Rapidly performed
–Rapid results
–Cheaper
–No architectural detail
–Small numbers of cells examined = representative?
–Limited assessment of tumour
type/grade
What are the advantages / disadvantages of histopathology?
–More invasive
–GA (or sedation) required
–Moderate tissue disruption
–More time consuming
–Delay in results
–More expensive
–Architecture apparent
–Larger sample size = More representative
–More accurate tumour type/grade
What are contraindications for doing fine needle aspirates?
- Bleeding
- If platelet count normal and no evidence of coagulopathy then usually OK
- I do not check PT / APTT prior to FNA unless problem suspected
- Monitor patients afterwards
- Risk of pneumothorax / urine / abscess leakage after
sampling - Small but not inconsiderable = Pneumothorax after lung FNA ~ 20%
- Risk of tumour transplantation deeper into tissue =
- Take care not to go through lesion
What are problems with fine needle aspirates?
- None diagnostic sample
- Around 20% of samples
- Always check if sending away
- None representative sample
- Especially heterogeneous lesion such as mammary tumours
- Healing lesions – meaning of large fibroblasts?
- Minimisation
- Take several samples
- Consider in context of patient and tumour
- Keep monitoring the lesion
- Bear in mind the strengths of cytology
What are different tissue biopsy techniques?
- Needle core biopsy
- Incisional biopsy
- Surface and pinch biopsies
- Punch biopsy
- Excisional biopsy
What are risks of biopsy?
- Haemorrhage
– Internal organs – FNA check platelets OK, Trucut of internal organ check coags also
– If there is evidence of bleeding check coags - Transplantation of tumour cells – Consider sampling path
- Compromise of future surgery
- Damage to adjacent structures
What are advantages of needle core biopsies?
*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 disadvantages of needle core biopsies?
*Small samples size compared to other biopsy
–Still 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
What are advantages of incisional biopsy?
- Good evaluation of architecture
- Histopathological grading
- Surgical approach allows selection of biopsy site
– Trucut “blind”
– Better sample, reduced risk - More tissue
– Can carry out special stains etc
What are disadvantages of incisional biopsy?
- GA normally required
- Increased time
- Both increase costs
What should be done with oncology monitoring?
- Active monitoring or watchful waiting must be active
– Only appropriate for benign lesions or after surgery were recurrence is unlikely
– Many owners are not confident or cannot do this well
– Nurse checks can be useful for this
– Prompt and appropriate action
What is the difference in stage + grade of tumour?
- Stage = how far has it got = clinical assessment of current disease burden
- Grade = histological features - activity, vascularity, invasion, necrosis, differentiation
How do you clinically stage tumours?
- Apply principles + basic knowledge of tumour biology
- T = primary tumour
- N = metastatic disease in local + regional lymph nodes
- M = distant metastatic disease
What is staging of T?
- Clinical examination
- Location and palpable extent – Well demarcated lesion?
- Fixation – To deep tissues / – To skin
- Ulceration
- Contrast radiography
- Ultrasonography
- Endoscopy / laparoscopy / thoracoscopy
- CT / MRI
What tumours tend to spread via haematogenous (via circulatory system)?
- sarcomas
- Malignant melanoma
What tumours tend to spread via lymphatic system?
- Local + regional lymph node spread
- Mast cell tumours
- Carcinomas
- Malignant melanomas
Where do lymph node metastases go?
- Spread to nearest node towards centre of body = towards thoracic duct
How would you stage N (regional lymph node metastases)?
- Palpation
– Relatively insensitive to metastatic disease
– Any palpable abnormalities – Size, Texture esp increased firmness, Fixation - Imaging
- Cytology/histology - required for diagnosis
What is lymphangiography?
– Detection of sentinel nodes using lymphangiography
– 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
What are common sites for metastases? (M)
- Lung
- Parenchymatous organs (liver, spleen, kidneys)
- Bone
- Skin
- CNS
- Distant nodes
With imaging what could you interpret as tumour in the liver?
Nodular hyperplasia = sample to confirm
What should be done to check for metastases to parenchymatous organs?
- Ultrasound + confirm with FNA
What are limitations of the NM system?
- Animals do not always present with the primary disease
- Metastatic disease
– Bony metastases
– LN mets in tonsillar carcinoma - Paraneoplastic syndromes - can dramatically reduce patients life
When would you refer tumours?
– Specialist expertise
– Advanced treatments
– Odd tumours / uncertain diagnoses
– Tricky clients
– More aggressive tumours
(most cases are managed well in general practice)
What are highly metastatic tumours?
- Oral/mucosal malignant melanomas
- Visceral + soft tissue haemangiosarcomas
- Appendicular osteosarcomas (dogs)
- High grade Mast cell tumours
- Subungual malignant melanoma (dog)
- Poorly differentiated mammary tumours (dog)
- Most mammary carcinomas in cats
- (Anal sac adenocarcinoma)
- (Prostatic carcinoma)
- (Digital squamous cell carcinoma)
What tumours are variably metastatic?
- Oral /axial OSA
- Thyroid carcinoma (dog)
- Patnaik intermediate grade Mast Cell Ts
- Injection site sarcoma
- Anaplastic sarcoma
- Insulinoma (most do!)
- Mammary carcinomas (dog)
- Apocrine adenocarcinomas
- GIT carcinomas
- Transitional cell carcinoma (TCC) of the bladder
- Liposarcoma
What are tumours with 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
What are tumours that don’t metastasise?
- Oral acanthomatous ameloblastomas – Aka basal cell carcinomas or acanthomatous epulids
- Haemangiopericytoma
- Schwannoma/neurofibroma
- BENIGN TUMOURS
