Cancer Treatment: Surgery & Radiotherapy Flashcards
what is an incisional biopsy
Removal of a portion of a mass for analysis prior to more definitive surgery
what is an excisional biopsy
Removal of an entire mass with some margin of grossly normal tissue for analysis and also for potential cure
what is cytoreductive surgery
Surgery designed to remove gross disease to prepare patient for radiotherapy
what are the 6 principles of oncology surgery
- Resect tumour with appropriate margin
- Plan biopsy so that tract cab be resected with tumour
- Consider scars from previous surgery, biopsies + drains as contaminated and include them with the primary resection
- Ligate the blood supply early to prevent dissemination
- Limit contamination of surgical field: change instruments, gloves between resection + reconstruction
- Limit the use of drains
why should you consider FNA for all skin masses
Low morbidity
Lipoma + mast cell tumour
Identify most tumours to cell type
Helps plan surgery
what if FNA is not sufficient (2)
- needle core biopsy
- surgical biopsy - incisional, excisional
how is a needle core biopsy done
Tissue collecting channel and outer cutting sheath
Spring loaded needles
Larger samples than FNA
Preserve architecture
what can needle core biopsies provide
Histopathological diagnosis
+/- grade: difficult to include normal tissue
what can an incisional biopsy provide
Preserves architecture
Deep biopsy to be representative
Staging: include normal margin
how is an incisional biopsy done
Wedge shaped incision
Deep is better than wide
Close with horizontal mattress sutures to compress tissues to prevent bleeding
how do you plan a biopsy
Ensure doesn’t impede subsequent surgery
Tract contaminated
Excise with margins
Take most direct route through skin
what is the radial margin
Margin of skin and associated fat
what is the size of the radial margin
1mm-3cm (occasionally 5cm)
what is the size of the radial margin dependent on
- tumour type
- predicted invasion
what is the anatomy of a skin mass
what is the deep margin
Biological barriers to tumour spread
Radial margin guidelines impractical
what are biological barriers to tumour
Collagen rich tissues:
Muscle belly
Fascia
Periosteum
Bone
(not cutaneous trunci muscle)
what should the margin of resection look like
avoid cone shaped
should go straight down
what are the options for margins of skin tumours (4)
- marginal resection
- local resection
- wide local resection
- radical resection
what is a marginal resection
Dissect just outside the pseudocapsule of tumour
how large are marginal resections
1-2mm margin
may leave microscopic deposits
what are the indications of marginal resections (2)
- lipoma (curative as very benign)
- cytoreductive beofre radiotherapy
what is a local resection for
Bengin, non-invasive masses
mammary tumour (dog), histiocytoma
how large are local resections
1cm radial margin
Down to but not through next unaffected fascial plane
what is a wide local resection for
for more invasive tumours
how large are wide local resection tumours
2-3cm radial margin
Excise deep fascial plane
what tumours are wide local resections for
Sarcoma
Mast cell tumour
what is radical resection for
very locally aggressive tumours
resection with very wide margins
what might radical resection require
Amputation (femoral osteosarcoma)
how large are radical resections
3-5cm radial margins
1-2 deep fascial planes
what tumour types are radical resections for
SCC
melanoma
feline injection site sarcomas
how large would radical resection of a feline injection site sarcoma be
Most invasive and aggressive tumour
Most radical veterinary surgery
5cm radial margins
2 deep fascial plane
Adjunctive radiotherapy/chemotherapy
how are body cavity tumours removed
Tumour within organ
Capsule may be effective barrier
Remove whole lobe or organ
when would complete surgical excision of a body cavity tumour be used
Aim usually to attempt cure
Complete surgical excision
Assumes tumour has not spread
Mainly aim in general practice with non-invasive tumour types
when would surgery be used as part of a multimodal treatment
Margins less important
Radiotherapy to preven local recurrence
Chemotherapy to limit metastatic disease deposits
Common in referral practice for invasive or malignant tumour types
what tumours are surgery + radiotherapy key for
Key treatment for invasive tumours:
Mast cell tumour
Soft tissue sarcoma
how do surgery + radiotherapy treat invasive tumours
Surgery removes bulk of disease
Radiotherapy kills remaining microscopic tumour deposits
Cytoreductive surgery
why use surgery and radiotherapy together
Radiotherapy is effective against rapidly dividing cells
Gross tumour deposits have mainly quiescent cells
Cytoreductive surgery removes all gross disease but anticipates that microscopic tumour deposits remain
Cytoreductive surgery is usually marginal resection or local resection
what are the options to submit to see if margins are sufficient
1:10 mass:fixative by volume
10% neutral buffered formalin
Submit all excised tissues
Mark margins with suture or ink
