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
