Oncologic surgery principles Flashcards
How common is cancer in dogs and cats?
1/3 dogs will get in lifetime and 1/4 cats
What are the 3 main areas for cancer treatment in small animals?
Medical, radiation and surgical management
- multimodal approach often indicated- can reduce the side affects of using just one approach
When is surgery and radiation preferred over chemo?
If the disease is local. Use chemo for systemic disease
What is the role of surgery in cancer treatment?
Can diagnose and treat solid tumors, can use for palliative treatment, or can use for prevention of cancer
What are the common signalments for cancer patients?
Often middle aged to older
-malignant tumors in young dogs tend to be more aggressive
-remember that age is not a disease! Must assess overall health status of each dog as they are
-breed and sex are not prognostic
What is a characteristic of most malignant tumors which make them hard to treat?
They have microscopic extensions into the surrounding tissue
Why is it important to focus on regional lymph nodes when evaluating a mass in a dog or cat?
Lymph node involvement may indicate metastasis- need FNA of lymph node for definitive answer
Can you have metastatic disease with normal lymph nodes?
YES- if worried about metastatic potential, get a sample from the regional lymph nodes
T/F: cancer can predispose patients to coagulopathies
TRUE
What are the methods for tumor diagnosis?
FNA, needle core biopsy, incisional biopsy, excisional biopsy
When should you pursue biopsy?
If the information received from it may change the choice of treatment, extent of treatment, as well as the owners willingness to treat
- biopsies are needed for tumor grading
What tumor type is FNA diagnostic for?
MCT
When are some conditions that FNAs are contraindicated?
If suspecting a TCC (can seed tumor into abdomen) or adrenal mass (often very sensitive)
T/F: you should assume a tumor is malignant until proven otherwise
TRUE- don’t want to make it worse if theres any chance
What biopsy tool is used to get a sample of bone?
Jamshidi
What are the disadvantages of needle core biopsies?
Sample is small, so may be non-diagnostic or non representative of the lesion
*take multiple samples for higher diagnostic accuracy
T/F: you can take biopsies of oral tumors without sedation or local anesthetic
TRUE
Define excisional biopsy
Resection of entire gross mass without definitive margins
-not recommended as if you don’t get good margins it will be hard to resect in entirety
-do not take any fascial planes as revision might be needed
-only consider in areas with adequate tissue coverage
What are the margins required for injection site sarcomas in cats?
5 cm minimum on each side, 2 fascial planes deep to mass
Why is local tumor imaging important?
assessment of tumor location, invasion into adjacent structures, can aid in surgical planning
-can look for distal metastasis
How does PET imaging work?
Glucose analogue stays in tissues that utilize a lot of glucose, like tumors
-also accumulates a lot in the brain
What does tumor staging depend on?
Local tumor characteristics, regional lymph node metastasis, or distant metastasis
What is the biggest mistake made with tumor planning?
Using too low of surgical dose
- your first attempt is your best chance at getting out the full tumor
What is recommended for most solid tumors?
Radical or wide resection
What is the difference between radical and wide resection?
Radical is removing the organ or part of the body where the tumor is located
-wide is where lateral and deep margins are made very wide to remove both the gross and microscopic tumor cells (amount you resect depends on type of lesion)
What margins are recommended for benign masses, grade 1 or 2 MCT, intestinal tumor
benign- 1 cm
MCT- 1 cm lateral per size of mass
intestinal: 4-8 cm
What is marginal exision?
Incomplete excision of a tumor with residual microscopic disease
- equivalent to an excisional biopsy
-avoid unplanned resections! know you might be leaving behind cancer cells and that other modalities of treatment may be indicated
Why is debulking not recommended?
Presence of macroscopic tumor usually makes adjunctive treatments less effective
What are some general principles you should keep in mind when performing surgery on tumors?
Avoid grasping tumor directly with instruments, avoid penetrating tumor capsule, avoid drains, avoid flaps without confirmation of complete margins, always change gloves and instruments in between biopsies or multiple mass resections
-always resect benign tissue before malignant
What is reccomended for pathologist examination of masses?
A combo of radial sectioning and tangential sectioning
What are the benefits of OHE prior to 3rd heat cycle?
Reduces or eliminates risk of mammary ovarian and uterine tumors
