Principles of oncological surgery Flashcards
List 5 roles of surgery in cancer management
Diagnosis (biospy) Resection for cure (definitive excision) Palliation (remove clinical signs) Debulking (cytoreductive therapy) Prophylaxis of neoplasia
Define biopsy
retrieval of cells or tissues form tumour to allow a Dx and prognosis (grading and staging) to plan appropriate therapy and allow owner to make decision about therapeutic options
Indications - biopsy - 3
- If treatment type (surgery/radiation/chemo) or extent (conservative/aggressive) would be altered by knowing the tumour type
- If owner’s willingness to treat animal would be altered ny knowledge of tumour type, grade, prognosis and clinical stage.
- If lesion is in ‘difficult’ area
What information can be gained from biopsy?
Neoplastic or non-neoplastic Benign/malignant? Cytological or histologic type Grade Margins (if excisional biopsy) Potential sites for metastases (if LNs or other organs sampled)
Guidelines - tumour biopsy
Site should lie within likely surgical field
Minimal risk of tumour dissemination
Fresh instruments for each site
Don’t worsen the prognosis
Longitudinal incisions for distal locations
Avoid tissue that would be difficult to resect or close
Large biopsy more likely to reach diagnosis
Careful tissue handling - avoid forceps and electrocautery
10% formalin fixation, tissues < 1cm thick
Detailed history
Define and outlien prophylactic tumour surgery
Remove tissue to reduce incidence of tumour occurence and recurrence rate
Normal or abnormal tissue
What does elective gonadectomy reduce the incidence of?
Decreases the incidence of mamary tumours, perianal adenomas, testicular tumours and willr educe the rate of recurrence of vaginal leiomyomas.
What might removal of lesions suspected to be pre-cancerous do?
May prevent the development of malignant disease susbsequently - eg. SCC in-situ from the skin of white cats and adenomatous rectal polyps.
Contraindications - tumour biopsy - 3
If treatment plan wouldn’t be changed
No change in owner’s willingness to treat
If biopsy is difficult
Indication - surgery with curative intent
Localised disease (only)
Advantages/disadvantages of complete surgical excision
ADVANTAGES: immediate cure, not carcinogenic, no local toxic effects, not immunosuppressive, better for large masses
DISADVANTAGES: local cure only, change in cosmesis, change in function
Principles - surgical excision - 5
- Establish Dx, plan surgery
- Perform surgery early in disease course
- First surgery has the best chance of success
- Adequate margins needed in 3D
- Margin of excision shouldn’t be compromised by concerns regarding closure
Why is it important to get tumour removal surgery right first time?
- untreated tumours have normal regional anatomy
- recurrent tumours may have seeded into previously non-involved tissue planes and it can’t be predicted where tumour cells will extend and a wider resection may be required.
- The most active and invasive parts of the tumour are at the periphery - incomplete excision leaves aggressive cells behind
- There is less normal tissue if surgery has been performed previously
Common reasons for failure of definitive tumour excision
Failure to plan surgery (usually failure to biopsy)
Failure to stick to the plan, usually concerns over closure
What information should be available before surgical procedure is selected?
Histologic type, grade and clinical stage
Expected local and systemic effects of above
Surgery indicated?
Cure possible?
Alternative and adjunctive procedures
What additional practical considerations are there for oncologic surgery? 9
Consideration of effect on cosmesis and function Pre-operative patient prep Dissection technique Reduction of tumour cell contamination in surgical field Avoidance of wound complications Vascular occlusion techniques Management of regional LNs Reconstruction of resulting deficit Evaluation of the resected tissue
What may interfere with local defence mechanisms to removal any remaining tumour cells after surgery?
haematoma, seroma or wound infection
Outline vascular and lymphati occlusion techniques
Ligate as early as possibly
Particularly important for tumours where exfoliation or dissemination of cells is likely or for tumours which usually metastasise via the haematogenous (sarcomas) or lymphatic (carcinomas) routes.
Theoretically, ligation of venous and lymphatic drainage should be performed before arterial suppy
Which tumour type is more likely to metastasise to regional LNs?
epithelial tumours much more likely than mesenchymal tumours.
Causes - regional lymphadenopathy
Metastasis - poor prognosis
Reactive hyperplasia - infection, inflammation, release of factors - may be indicative of a beneficial response
Result of lymphadenopathy due to tumour metastasis
generally results in complete effacement by tumour cells and a Dx may be made by FNA
Indications - LN removal
- If positive for a tumour and is not fixed to surrounding tissues (generally alone, en bloc resection of tumour, LN and intervening lymphatics may be performed in some cases)
- Normal-appearning LNs which drain the primary tumour maybe sampled to stage the tumour
Contraindications - LN removal
- LNs in critical areas which are fixed to the surrounding tissue. Biopsy or leave in situ
Prophylactic removal of normal-appearing LNs without intention of sampling them to stage the tumour has no benefit and may reduce any beneficial host response to the tumour.
Name 3 common types of surgical margin
Local excision
Wide local excision
Radical local excision
Define local excision
the tumour is removed through its natural capsule, immediate boundaries or with the minimum of adjacent tissue
LOCAL EXCISION:
Indications
Contraindications
INDICATIONS: benign tumours with no tendency for local infiltration - lipoma, histiocytoma, sebaceous adenoma
CONTRA-INDICATIONS: invasive benign tumours, all malignant tumours.
Define wide local excision
tumour is removed with a substantial margin of surrounding tissue, margins depend on individual tumour.
Anatomical determinants may dictate whether the selected margins will be feasible from a practical point of view, but they should never be the primary determinant in the selection of the appropriate margin.
WIDE LOCAL EXCISION:
Indications
Contraindications
INDICATIONS: benign tumours with the capacity for local infiltration (infiltrating lipoma), malignant tumours with limited potential for infiltration (WD SCC)
CONTRA-INDICATIONS: malignant tumours with the potential for local infiltration
Define radical local excision
tumour is removed together with margins that extend into adjacent fascial planes which are undisturbed by tumour growth.
RADICAL LOCAL EXCISION:
Indications
Contraindications
INDICATIONS: tumours whose rapid radial expansion results in teh development of a circumferential zone of compressed tissue or pseudocapsule
What is a pseudocapsule
the capsule around the tumour
contains tumour cells
using this as a guide in the selection of surgical margins is likely to result in complete excision.
Sarcomas (extend along rather than locally through fascial planes)
Techniques for radical local excision
Compartmental excision
Muscle group excision
Amputation
What is compartmental excision
A type of RADICAL LOCAL EXCISION
Tumour is removed within an intact anatomic compartment such that it is surrounded on all aspects by fascial planes that have not been disturbed by the growth of the tumour.
All BVs and nn which lie within the compartment are removed intact during the procedure.
Generous margin of overlying skin removed where appropriate.
Define muscle group excision
the tumour is removed along with the entire muscle it involves
INDICATIONS = small tumours involving muscle bellies in which the fascial planes haven’t been breached or have been breached on an outer aspect where the tissue may also have been removed.
Indications - amputation
Large tumours for which a compartmental of muscle group excision is not practical
- Where a radical excision requires resection of a bone or joint
- The management of tumour recurrences where the anatomic compartments have been disturbed by previous surgery and recognition of fascial planes would be difficult
- resections that would severely impair limb function
- malignant tumours with signficant capacity for local infiltration
What are resected tumour tissues evaluated for?
Histological type Histological grade Regional LN status Margins Vascular or lymphatic invasion
What is cytoreductive therapy
Cytoreductive (debuling therapy) is the planned incomplete removal of the tumour to improve the efficacy of other treatment modalities (chemo or radiotherapy).
The term ‘debulking’ should be avoided so that cytoreductive surgery and palliative surgery (both of which remove most but not all of the tumour) may be considered separately.
When might surgery be regarded as cytoreductive? 4
IF:
- complete excision is precluded by the need to retain essential anatomic structures
- surgery is performed following a previous unsuccessful attempt at excision
- local recurrence is likely
- tumour type has a high rate of local recurrence
Define palliative surgery
an attempt to improve patient’s QoL but not necessarily their length of life
Pain relief or improve function
