Oncology: Approach to the Cancer Case Flashcards
Why do patients die of cancer?
- Delayed/erroneus diagnosis
- Failure to treat- primary disease, metastatic spread
- Ineffective treatment
- Owner decided not to treat
What basic diagnostics can be done for cancer?
- History
- Physical examination
- Minumum database- blood count, biochem, urinalysis
- Biopsy- cytology, histoloy
- Imaging
What advanced diagnostic tools can be used for cancer?
- Immunochemistry- cytochemistry and histochemistry
- Flow cytometry
- PCR
- Electrophoresis
What are the 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 any body opening
- Bad odor- especially mouth
- Difficulty eating or swallowing
- Reluctance to excercise or loss of stamina
- Difficulty breathing, urinating, defecating
- Change in behaviour
What should be noted when examining a potential lesion?
- Measure and record size and location of all lesions
- Assess invasiveness and attachment to underlying tissues
- Look for characteristics associated with malignancy
If cancer is suspected what should be checked on a general examination?
- General condition and BCS
- Palpation over the whole body
- Palpation of LNs 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
What can haematology and biochemistry show for cancer patients?
Haematology- only diagnosis if patient has leukaemia
* required prior to chemo
Biochem is never diagnostic
* concurrent disease
How is cancer diagnosed?
- FNA- cytology
- Tissue biopsy- histopathology
What are the pros and cons of cytology vs histopathology
Cytology
* Not as invasive
* Only manual restaint
* Cheaper
* Limited assessment of tumour type/grade
Histopathology
* GA required
* More accurate tumour type/grade
* Invasive
What is generally the purpose of cytology vs histopathology and vice versa?
Strength of cytology is generally guiding diagnostics and treatment planning- prior to surgery
Histolopathology- final diagnosis and guiding post surgical treatment
- When is needle off FNA indicated? (not aspirated)
- What do you need to be careful of?
- Lymph nodes, suspected round cell tumours
- Do not go through lesion (seeding)
Multiple directions, cover needle hub as you with draw
- When is FNA with aspiration indicated?
- How much pressure is indicated?
- Suspect solid tumuors, when the needle off gave poor yield
- 1cc of negative pressure (1ml)
Multiple directions, don’t go through lesion, release suction before taking needle out
What are contraindications for FNA?
Bleeding
* if platelet count normal and no evidence of coagulpathy then ok
Risk of pneumothorax/urine
Tumour transplantation deeper into tissue
How is a smear made from an FNA?
5ml air to expel sample
Use weight of slide to spread the sample
How can cytology samples be taken?
- Intra-op or PM
- Ulcerated superficial lesions
- Nasal biopsies
- Airway lesions
Describe the technique for cytology impression smears
- Collect sample
- Blot surface- remove debris if ulcerated lesion, remove blood
- Dab against slide- make multiple spots
What are the problems of FNA?
None diagnostic
None representitive- heterogenous lesions
What are the 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 of future surgery
- Damage to adjacent structures
How can a needle core biopsy be taken?
Trucut needles- two handled operation, needle assistance
Cooks/Arnolds biopsy needled- semi-automated
What are the advantages and disadvantages of needle core biopsies?
Adv
* Comparatively inaccessible tissues can be accessed percutaneously
* Larger samples
* Multiple samples can be taken
* Superficial lesions can be biopsied under sedation and local anaesthesia
Dis
* Small samples compared to other biopsied
* Greater risk of FNA
* Operator skill required- US guided
- What needle is needed for bone core biopsy?
- What is the risk?
Jamshidi needle
Pathological fracture risk
What is incisional biopsy?
What is the most common technique?
- Surgical removal of segment of solid tissue
- Technique varies with tissue/lesion
- Wedge biopsy most common
What are the advantages and disadvantages of incisional biopsy?
Adv
* Good evaluation of architecture
* Histopathological grading
* Surgical approach
* More tissue
Dis
* GA normally required
* Increased time
* Both increase costs
What are the ‘rules’ of incisional biopsy?
- Position incision so entire biopsy tract can be removed on subsequent surgery
- Make incision large enough to harvest the sample without excessive tissue manipulation
- Minimise instrumental manipulation of biopsy
- Avoid diathermy
- Include normal tissue if possible
- Ensure adequate fixation
What accessible surfaces can pinch and grap biopsies be used?
- Respiratory tract
- Gastrointestinal tract
- Urogenital tract
Direct visualisation
Endoscopy
Blind
Laparoscopy/thoracoscopy
How can surface pinch and grab biopsies be done for nasal tumours?
- Measure distance to insert from radiographs
- No further then medial canthus (eyes)
- Cats- cut off urinary catheter
- When are endoscopic biopsies mainly used?
- When are punch biopsies used?
- Mainly mucosa- very small
- Cutaneous/superficial- rotate in one direction
What is an excisional biopsy?
Attempted surgical extirpation of a lesion or mass followed by removal of biopsies of whole sample
Often results inadequate excision
When is excisonal biopsy indicated?
- Haemorrhaging splenic masses
- Mammary tumours
- Pulmonary tumours
Widely used in treatment of skin tumours
Submit whole lesion- tag/label/pain questionable margins
What are the contraindications of excisional biopsies?
- 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 is the ideal first diagnostic step for this case?
FNA and Cytology
What is the ideal first diagnostic sample for this lesion
Exisional biopsy after staging
What is followed after diagnosis of cancer?
- Client communication
- Active monitoring
- Staging
- Tumour related complications
- Comorbidities and general health
How are solid tumours clinically staged?
Process by which we assess the extent of disease
* T- primary tumour
* N- metastatic disease in local and regional lymph nodes
* M- distant metastatic
Grade does not mean stage
Usually further divided- T1-4 which gives prognosis
How can T be clinically staged?
- Clinical exam
- Location and palpable
- Fixed- to deep tissues/skin
- Ulceration
- Imaging
How much bone lysis is needed before it can be identified on radiographs?
60%
How can T stage be imaged?
- Plain radiographs
- Contrast- urogen, GI, CNS
- Ultrasound- abdomen
- Direct visualisation- endocsope, laparoscope
- Advanced imaging- CT/MRI
How are tumour metastasis divded?
- Haematogenous- blood
sarcomas, melanoma
Lung, kidneys - Lymphatic- lymphatic system
Mast cell tumours, carcinomas, melanomas
Lymph nodes
How can N be clinically staged?
- Palpation
- Imaging
- Cytology/histology
FNA/biopsy
How can clinical stage N be imaged?
- Thoracic radiograpy- moderate to marked enlargment of nodes
- Abdominal radiography- medial iliac lymph node enlargment
- US- mesenteric lymph nodes
- Lymphangiography- sentinel nodes- inject contrast find what nodes drain
What route do most lymph node metastasis follow?
Spread by the lymphatic route go to the nearest node towards the centre of the body (towards the thoracic duct)
can skip a node
affected nodes can be resected ‘en bloc’
What are common sites for distant metastasis (M)
- Lung
- Parenchymatous organs- liver, spleen, kidney
- Bone
- Skin
- CNS
- Distant nodes
Clinical signs are difficult to identify
How can metastasis to parenchymatous organs be clinically staged to M?
US superior
Confirm by FNA
What are the limitations of the TNM system?
- Animals do not always present with the primary disease
- Metastatic disease- bony mets, LN in tonsillar carcinoma
- Paraneoplastic syndromes
When should referral be considered?
- Specialist expertise
- Advanced treatments
- Odd tumours/uncertain diagnosis
- Tricky clients
- More aggressive tumours
How likely are the following cancers to metastasise?
* Oral/mucosal malignant melanoma
* Visceral and some other soft tissue haemangiosarcoma
* Appendicular oesteosarcoma
* High grade MCTs
Highly
How likely are the following neoplasms to metastasise?
* Subungual malignant melanoma
* Poorly differentiated mammary tumour
* Most mammary carcinomas
* Anal sac adenocarcinoma
* Prostatic carcinoma
* Digitial squamous cell carcinoma
Highly
What cancers do not metastasise?
- Oral acanthamatous ameoblastomas
- Haemangiopericytoma
- Schwannaoma
- Benign tumours
