Principles of Surgical Oncology Flashcards
Why are recurring tumours after initial surgery more locally invasive? (2)
-Altered vascularity
- Local immune response
What are the 4 categories in Enneking’s classification?
- Intracapsular debulking
- Marginal
- Wide
- Radical
What was the basis of Enneking’s classifcation?
The macroscopic relationship of the margin to the tumour and its pseudocapsule.
An intralesional margin would be obtained when..
the dissection passes within the lesion, which means the tumour’s pseudocapsule has been opened and violated during surgery. Either macroscopic or microscopic tumour tissue is usually left at the margins, and there may be contamination of the exposed tissue planes.
What is the most common intralesional procedure?
A diagnostic incisional biopsy or by subtotal “debulking” resection of the tumour.
What is cytoreductive surgery?
the incomplete removal of a tumour
When is cytoreductive surgery a practical consideration? (3)
Prior to:
Cryosurgery
Chemo
Radio
When is cytoreductive acceptable as a treatment?
BENIGN conditions (otherwise need to be followed with other tx.)
What does a marginal margin result from?
a procedure in which the tumour is removed through the pseudocapsule or “reactive zone” around the tumour.
When a marginal resection is performed for soft tissue sarcoma, there is a possibility of..
microscopic residual tumour
Why will marginal margins be performed? (2)
- excisional biopsy
- close to critical structures, including nerves, vessels, and organs.
What is a wide margin?
A wide margin is accomplished by a procedure in which the lesion is resected with the surrounding normal tissue.
What is a radical margin?
A radical margin in achieved by a procedure in which the tumour is resected with wide margins plus the entire tissues/organ in the anatomic compartment. Radical resection is defined as the removal of a body part.
Define wide resection
a tumour is resected along with surrounding normal tissue (e.g. a soft tissue sarcoma resection)
Define marginal resection
a tumour removed through a pseudo capsule or reactive zone (e.g. for a tumour close to critical structures)
Define intralesional resection
dissection passes within the lesion (e.g. debulking surgery)
Define radical resection
tumour is removed by removing an entire body part (e.g. limb amputation)
What surgeries are considered curative-intent surgeries? (2)
Wide + radical resections
What are the oncology aims of wide/radical resections?
Resecting macroscopic and microscopic disease, including biopsy tracts
Following skin/subcut incisions - what should we do with skin edges and why?
Protective drapes or swabs should be placed on skin edges to prevent tumour seeding.
Why is prompt haemostasis crucial in tumour removal?
To prevent the release of tumour emboli into the circulation (especially for tumours with a good vascular supply, such as splenic and lung tumours)
What should be performed to dilute residual exfoliated cells?
Wound lavage
Why should drains be used sapringly in oncological surgery?
disrupt deep and lateral tissue planes distant to the surgical field.
What should the surgeon do fallowing tumour excision to prevent contamination with exfoliated tumour cells?
Change - gloves, drapes and kit.
In the most recent studies, how is “histologically free margins” define?
Both quantitatively (e.g. 4 mm) and qualitatively (e.g. normal adipose tissue).
What lateral margins should be taken for benign tumours?
1cm
What lateral margins for most malignant carcinoma?
1cm
What lateral margin for STS?
3cm
Lateral margins for Grade I and II MCT?
2cm
What should deep margins contain?
1 fascial plane
What are resistant to neoplastic invasion and area good natural tissue barrier?
Connective tissues, such as muscle fascia and bone
How are lateral margins determined with modified proportional margin (MPM) approach?
The surgeon measures the widest diameter of the tumour and this measurement is used as the lateral margin for excision.
Why shouldn’t tumours be “shelled out” - particular STS?
Surrounded by a pseudo capsule of compressed, viable neoplastic cells and a reactive zone;
Select the tissues that provide a good natural barrier to tumour invasion.
Muscle fascia
Bone
Generating tissue for histopathology involves five broad phases which might impact the pathologist’s ability to collect reliable data. They are:
- immediate post-excisional period;
- tissue fixation;
- trimming (sectioning of the fixed gross specimen so that tissue adequately fits into a cassette)
- histologic processing (post-fixation processing, microtomy and slide mounting);
- morphologic slide evaluation.
How should large tumour histo samples be fixed?
Slice into sections more than 1 cm thick to facilitate adequate fixation, but to maintain the ability of the pathologist to orient the sample and assess margins, the slicing should not be full thickness
How should samples be submitted to orientate pathologist with margins?
Mark with sutures or dye
What information should be submitted with a histo sample? (6)
- Location
- Size
- Shape
- Texture
- Relationship to surrounding structures
- if required - a picture of margins in relation to site
Prior to formalin fixation - how much does the tissue shrink by?
15.6%
Why does a tumour shrink following removal?
myofibril contractility
tissue elasticity
