Kapitel 25 - Introduction to oncologic surgery

Question 1

How can oncogene be activated?

Answer 1

chromosomal translocation, gene amplification, point mutations, and viral insertions

Question 2

What is phenotypic characteristics of tumors?

Answer 2

1) self-sufficiency in growth signals
(2) insensitivity to antigrowth signals
(3) tissue invasion and metastasis, (4) limitless replicative potential
(5) sustained angiogenesis
and (6) evasion of apoptosis

Question 3

What are the phases of interphase and what are the critical checkpoint called and when does it occure?

Answer 3

G1, G2 and S

It is called the restriction point and happens at G1

Question 4

What are the terms applied to genetic factors causing cancerformation?

Answer 4

Initiation, promotion and progression

Question 5

Which cancers have true genetic heritability in dogs?

Answer 5

Osteosarcoma of Scottish Deerhounds and renal cystadenocarcinoma and nodular dermatofibrosis in German Shepherd Dogs

Question 6

What are the four mechanisms that can transform a protooncogene to an oncogene?

Answer 6

1) retrovirus-mediated transduction
(2) a translocation mutation
(3) amplfication, or
(4) proviral insertion

Question 7

What are characteristics of dysplastic changes in cells?

Answer 7

anisocytosis, anisokaryosis, mitotic figures, and chromatin changes

Question 8

For what malignancies can FNA be used as a definitive diagnosis?

Answer 8

lymphoma, melanoma, mast cell tumor

Question 9

in what cases should cytology be interpreted with cuasion?

Answer 9

In in presence of severe inflammation because it can induce changes in normal cells that have malignant features.

Question 10

What value do you have from preoperative biopsy and give an example when preoperative biopsy will affect case management

Answer 10

Evaluation of degree of invation, metastatic potenistion and biological activity (eg. The release of heparin or histamine from mast cell tumors). This can influence how you decide to treat the patient.

Examples are oral tumors.

Question 11

What is the different between incisional and excisional biopsy and what are some advantages/disadvantages?

Answer 11

Incisional biopsy is the removal of a portion of a tumor by sharp incision. Disadvantages of the incisional biopsy approach are that it requires that a second surgical procedure be performed to excise the mass and it may create a direct communication between the tumor tissue and surrounding normal tissue, possibly increasing the chance of local recurrence.

Excisional biopsy is the removal of the entire tumor along with a surrounding barrier of normal tissue. The main advantage of this technique is that biopsy and gross tumor removal are performed in a single procedure. The primary disadvantage is that if the tumor is highly invasive and the surgeon does not know the identity of the tumor, the level of surgical aggressiveness may be inadequate for complete excision. Such an excision has been termed an unplanned excision

Question 12

What staging system is most used and what does the letters stand for?

Answer 12

Tumor-node-metastasis staging system (TMN)(by WHO).
T stand for the characteristics of the primary tumor
N stands for regional lymph nodes
M represent distant metastasis.

Question 13

Name some comorbidity conditions

Answer 13

Neurologic disease is contraindicated for limb amputation, anemia has shown to have a poorer survival rate in humans,

Question 14

When should blood transfusion be considered?

Answer 14

In animals with acute intraoperative blood loss (i.e., blood loss >25% of blood volume or packed cell volume <20%) and hypotension (mean arterial pressure <80 mm Hg or systolic arterial pressure <100 mm Hg)

Question 15

Why should local anaestasia not be used intratumorally?

Answer 15

It will distort tumor architecture, will increase the difficulty of histopathologic interpretation, and may potentiate metastasis.

Question 16

How is surgical resection categorized?

Answer 16

Intraleasion (debulking), marginal, wide and radical.

Question 17

What margins are recommended?

Answer 17

1-cm lateral margins are recommended when excising benign tumors and 2- to 3-cm lateral margins are recommended, when possible, when excising soft tissue sarcomas and mast cell tumors. Lateral margins of 1 cm are usually sufficient for most carcinomas; 1-cm lateral margins usually result in complete excision of most low-grade mast cell tumors and soft tissue sarcomas

Deep margins are determined by natural tissue barriers because deep margins (1 to 3 cm) may not be possible in regions such as the extremities (e.g., limbs, head). Fat, sub­cutaneous tissue, muscle, and parenchymal tissue do not provide a barrier to tumor invasion and are not adequate for deep margins. Connective tissues, such as muscle fascia, cartilage, and bone, are resistant to neoplastic invasion and provide a good natural tissue barrier. Hence, deep margins should include a minimum of one fascial plane, and two fascial planes are recommended for surgical resection of injection-site sarcoma

Question 17

What margins are recommended?

Answer 17

1-cm lateral margins are recommended when excising benign tumors and 2- to 3-cm lateral margins are recommended, when possible, when excising soft tissue sarcomas and mast cell tumors. Lateral margins of 1 cm are usually sufficient for most carcinomas; 1-cm lateral margins usually result in complete excision of most low-grade mast cell tumors and soft tissue sarcomas

Deep margins are determined by natural tissue barriers because deep margins (1 to 3 cm) may not be possible in regions such as the extremities (e.g., limbs, head). Fat, sub­cutaneous tissue, muscle, and parenchymal tissue do not provide a barrier to tumor invasion and are not adequate for deep margins. Connective tissues, such as muscle fascia, cartilage, and bone, are resistant to neoplastic invasion and provide a good natural tissue barrier. Hence, deep margins should include a minimum of one fascial plane, and two fascial planes are recommended for surgical resection of injection-site sarcoma

Question 18

What is marginal resection?

Answer 18

Marginal resection is performed by dissecting just peripheral to the tumor pseudocapsule in the reactive zone. Such an approach is successful with benign tumors such as lipomas

Question 19

What is the differences between planned or unplanned marginal resection?

Answer 19

Planned marginal resection is performed when the tumor type is known based on preoperative biopsy and unplanned when its not known.

Question 20

What lateral margins should be used in grade 1, 2 and 3?

Answer 20

• 1 and 2 –> 2 cm
• 3 –> 3 cm

Question 21

List the 4 techniques used to manage unplanned marginal resections that result in incompletely excised malignancies:

Answer 21

1) no treatment, (2) staging resection of the surgical wound, (3) wide resection of the surgical wound, and/or (4) combination with radiation therapy or chemotherapy

Staging resection involves excision of the surgical wound with ≤10-mm margins

Question 22

Should drains be used after tumor excision?

Answer 22

They should be avoided since they increase the risk for tumor seeding.

Question 22

Should drains be used after tumor excision?

Answer 22

They should be avoided since they increase the risk for tumor seeding.

Question 23

What is debulking surgery?

Answer 23

Debulking surgery is defined as the incomplete resection of a tumor with residual gross disease.

Question 24

What is the sentinel lymph node?

Answer 24

The sentinel lymph node concept is based on the theory that the metastatic process occurs in an orderly progression within the lymphatic system, with tumor cells draining into a specific lymph node (i.e., the sentinel lymph node) in a regional lymphatic field before draining into other regional lymph nodes.

Question 24

What is the sentinel lymph node?

Answer 24

The sentinel lymph node concept is based on the theory that the metastatic process occurs in an orderly progression within the lymphatic system, with tumor cells draining into a specific lymph node (i.e., the sentinel lymph node) in a regional lymphatic field before draining into other regional lymph nodes.

Question 25

What suture material should be avoided?

Answer 25

multifilament suture materials are associated with increased risk of local tumor recurrence caused by trapping of tumor cells in the interstices of the braided material. Monofilament suture material or staples are preferred for ligation and wound closure

Question 26

What is the preferred was of wound closing and when can flaps be safely used?

Answer 26

• Primary wound closing
• Once there is no histologic evidence of tumor, then pedicle or axial pattern flaps can be safely used to reconstruct the soft tissue defect. If reconstructive surgery is used at the time of tumor resection and excision is incomplete, then both the flap donor site and the tumor resection site are considered contaminated

Question 27

What are the most useful reconstructive techniques?

Answer 27

tension-relieving procedures (e.g., tension-relieving suture patterns and releasing incisions), local pedicle flaps (e.g., advancement flaps, transposition flaps, flank fold flaps), axial pattern flaps (e.g., thoracodorsal and caudal superficial epigastric axial pattern flaps), and free meshed skin grafts

Question 28

Which three can delivery of surgical margins be split into?

Answer 28

metric approach (distance from primary tumor in three dimensions), the barrier approach (use of resistant anatomic boundaries; e.g., fascia, periosteum, air), and the metric/barrier hybrid (e.g., 2-cm wide skin and one fascial plane deep)

Question 29

what are the excisable margins for small intestinal tumours?

Answer 29

4-8 cm of health looking bowel.

Question 30

How is immunohistochemistry used in oncology?

Answer 30

The use of antibodies can help determine the cell of origin.

Question 31

What is the risk of local recurrens of soft tissue sarcomas with residual cancer cells compared to cleanly excised tumors?

Answer 31

10,5 times more likely

Question 32

What is the reported recurrence rate following complete surgical excision of grade 2 mast cell tumors?

Answer 32

11%
However the reccurence of the tumors is 18-35% even if incomplete exciced

Question 33

What does neoadjuvant and adjuvant therapy stand for and what are the aim?

Answer 33

Neoadjuvant are therapies that are done before surgery and adjuvant are therapies after the surgery

Neoadjuvant therapy is rarely used in vet medicine. Aimed to reduce tumour size, decrease risk of satellite and in-transit metastases

Adjuvant are aimed at eliminating residual microscopic tumour burdens.

Question 34

What are the disadvantages of neoadjuvant radiation therapy and when is it od advantaged?

Answer 34

It has deletions effects on regional vascularity and is associated with delayed wound healing and other wound complications.

In some feline injection site sarcomas.

Question 35

For what tumours has adjuvant chemotherapy been used in veterinary medicine?

Answer 35

canine osteosarcoma, hemangiosarcoma, and high-grade mast cell tumor and soft tissue sarcoma.

Question 36

When should adjuvant chemotherapy start?

Answer 36

10-14 postop

Question 37

Give examples of commonly used chemotherapeutic agents and their mechanism of action

Answer 37

• Alkylating agents - Alkylating agents work by inserting bulky alkyl groups onto DNA/RNA strands, leading to interference in DNA replication and RNA translation
• Microtubule inhibitors (Vinca alkaloids and Taxanes) - Vinca alkaloids are microtubule inhibitors that affect the spindle apparatus during mitosis and thus are considered to be cell cycle specific.
• Antibiotics and anthracyclines – multiple mechanism of action including topoisomerase inhibition, DNA intercalation, and formation of iron-mediated free radicals that lead to DNA damage
• Platinum agents - These agents cause covalent binding of DNA strands, which restricts DNA replication and, ultimately, protein synthesis.
• Bisphosphonates - This class of drugs inhibits osteoclast activity and subsequently suppresses bone resorption, leading to improved bone mineralization.

Question 38

What is the fatal rate of chemotherapies?

Answer 38

1%

Question 39

In general, what is the bone marrow nadir for most chemotherapeutic drugs?

Answer 39

approximately 7 days, with carboplatin being the exception at 10 to 14 days

Question 40

What is the most common acquired mechanism of resistance in dogs? What breeds have an increased likelihood of this gene mutation?

Answer 40

The multi drug resistant gene (MDR-1)

Herding breeds such as Collies, Shelties and Australian cattle dog.