Ch 82 Tumor surgery Flashcards
considerations
- first surgery has the best chance of complete removal and should therefore be well planned.
- Incomplete resection > only diagnostic purposes (biopsy) because regrowth of the tumor will usually occur quickly > partly in response to enhanced (neo)vascularization of the tumor bed
- central (bulk) portion of tumor relatively indolent and slow growing,
- tumor edge contains cells displaying a “migratory or invasive phenotype” > micro-environment that facilitates aggressive growth behavior
surgical margins
- most important factor in local tumor control is the surgical wound margin
- debulking
- marginal
- wide
- radical
- depends on tumor type and grade (i.e., invasiveness) and on the type of tissue (e.g., fat versus fascia)
- high probability of local recurrence, depth = at least one tissue plane away from the tumor
- considerable variation in published data about what is considered a complete tumor excision on histologic margin evaluation
surgical principles
biopsy
- histologic type and grade often predictive for biologic behavior = important for treatment planning
- incisional biopsy prefered
- Fine needle aspiration biopsy tracts are of less importance in regard to tumor spread.
- Contamination of needle tracts > transitional cell carcinomas and pulmonary adenocarcinomas
principles
- Open wound management after wide excision of distal extremity tumors can have very good functional and oncologic outcome > can be slow, relatively fragile new skin and wound contracture
- Faster wound healing with better skin quality with graft
- Careful and correct tissue handling must be applied to avoid spreading of tumor cells
- Early ligation of larger, tumor-associated blood vessels
- if tumor bed was incised during surgery, instruments and gloves should be changed +/- lavage of wound bed
- 5% to 10% formaldehyde;
- 2 cm scar revision margin
Factors Affecting Wound Healing
- chemo
- radiation
- tumour related (residual neoplastic tissue infiltrating, cytokines and bioactive substances (e.g., mast cell degranulation), cancer cachexia, and other paraneoplastic syndromes
Likewise, full-thickness intestinal surgery (gastrotomy/enterotomy and/or resection-anastomosis) in 70 cats with alimentary lymphoma was not associated with an increased risk for wound dehiscence.
What tissue appears most sensitive to healing issues with chemotherapy?
At what stage post-op is it generally recommended to start chemotherapy?
- Intestinal tissue
- 7-10 days after surgery > arbituary as sudies in human have shown no heling consequnces with peri-op chemo and potentially interferes with metastatic pathways
What is the gereral recommendation of timing of radiation therapy before and after surgery?
- After surgery: 1-3 weeks (Effects on wound healing most distinct in the acute inflammatory and proliferative phase, less severe during granulation and remodeling)
- Before surgery: Discontinue for 3-4 weeks
List tumour-related factors which may impact wound healing
Residual neoplastic tissue
Tumour-related cytokines
Cancer cachexia
Paraneoplastic syndromes
Tumour size
Tumor Staging
- uses the tumor-node-metastasis (TNM) system
- size and invasiveness (T),
- involvement of regional lymph nodes (N),
- presence of distant metastases (M).
- routine blood work
- signs of possible paraneoplastic syndromes
- All skin and subcutaneous masses should be investigated cytologically by fine needle aspiration biopsy
- Most tumors can be diagnosed cytologically.
- definitive diagnosis of tumor type and grade (malignancy) should be confirmed through histology.
List the 4 classifications of tumours based on cell origin
Mesenchymal
Epithelial
melanocytic
round cell
What is the estimated diagnostic accuracy of FNA cytology of skin neoplasms as compared to histo?
FNA has a high predictive value
over 90%
How do epithelial and mesenchymal neoplasms tend to metastasise?
- Mesenchymal - haematogenous
- Epithelial - Lymphatics
Exceptions: osteosarcoma, synovial cell sarcoma spead to lymph nodes
L.n. FNA
Fine needle aspiration cytology can be very sensitive to diagnose lymph node metastasis, compared to manual palpation, which has much lower sensitivity
CT/MRI
extent of disease
- to establish better insight into tumor margins and invasiveness
- assess l.n.
- screening for thoracic metastasis
What technique can be used for real-time intra-op margin assessment?
Near-infrared fluorescense imaging
What sized thoracic nodules can be detected on CT and rads?
CT: 1-2mm
Rads: 5-9mm
Lymphatic System
- functions: transport and immune response
- part of the cardiovascular system
- part of the host immune defense system
lymphatics
- initial lymphatics are present as blind-end sinuses
- no tight junctions between the cells,> permit extracellular fluid, macromolecules, and cells to drain
- lymphatics > collecting ducts > lymph nodes > thoracic duct
- lymph flow is active and passive
lymph node
- one or two at each nodal station.
- capsule (smooth muscle fibers), septa and trabeculae, the hilus and Internally, a cortex and medulla.
- B cell, T cells, macrophages and plasma cells
What cells make up the germinal centers of a lymph node?
B-lymphocytes and plasma cells