Final Exam-Oncology Flashcards
What are the cancer statistic for dogs and cats?
1 out f 3 dogs and 1 out of 4 cats get cancer
What breeds of dog have a lifetime risk of 50% in developing cancer in their lifetime?
Golden retrievers
Boxers
What types of cancers do dogs in urban areas have a higher risks of having?
Tonsillar
What increases the risk of hemangiosarcoma in dogs?
Radiation
What type of cancer increases in dogs you have been exposed to topical insecticides and dips?
Bladder
How can bladder cancer be prevented?
Eating vegetables, especially carrots to prevent transitional cell carcinoma
What are the three steps of carcinogenesis? Which are reversible?
- Initiation - reversible
- Promotion
- Progression
What are the 6 hallmarks of cancer?
- Sustained proliferative signaling
- Resisting cell death
- Inducing angiogenesis
- Enabling replicative immortality
- Activating invasion and metastasis
- Evading growth suppressors
What occurs during the initiation stage of carcinogenesis
The carcinogen interacts with the cellular DNA and causes damage.
Why are initiated cells not cancer cells yet?
There is no autonomal growth ability
What occurs during the promotion stage of carcinogenesis?
Clonal expansion of initiated cells by mutated genes. This action alone ( independent of initiation) can not cause tumor development.
What occurs during the progression stage of carcinogenesis?
Tumor obtains ability to grow and invade tissue and metastasis to distant locations with increased genetic instability and nuclear alterations of the cells.
What occurs during sustained proliferative signaling in cancer cells?
Cancer cells produce growth factor ligands resulting in autocrine proliferation and paracrine signaling to the stroma around the cell and to other cells.
How can cancer cells die?
- Apoptosis
- Necrosis
- Autophagy
Which way in which cancer cells die requires ATP?
Apoptosis
What insult must occur in order for their to be apoptosis, necrosis or autophagy of a cancer cell?
Apoptosis: Chemotherapy, radiology, withdrawal of growth factors, death signals
Necrosis: Ischemia-reprefusion
Autophagy: Starvation
Which genetic mutation causes most cancer?
P53 mutation
What does P53 do for cells?
It can recognize damaged DNA , repair, or signal for apoptosis
When is angiogenesis not suppressed?
- Female cycle
- Inflammation
- Wound healing
- When cancer cells are located 2 mm or more from a vessel become hypoxic and release mediators
What is angiogenic switch-shift?
Activators of angiogenesis turn the switch on, while inhibitors, turn it off. There is a balance between these, but in cancer it switches to on.
What is the difference between angiogenic vessels and primary vessels?
They are tortuous, dilated, irregularly shaped. Blood pressure may be slow/intermittent, and lead to inefficient delivery of drugs/radiation (makes it harder to treat).
What are some drugs that can be used to treat cancer via inhibiting angiogenesis?
- Bevacizumab
2. Palladia
What is the angiogenesis-metronomic therapy?
Administration of low dose chemotherapy and anti-inflammatory COX2 on a daily or every other day dose
What is angiogenesis-metronomic therapy effective against?
- Circulating progenitor cells
2. Circulating endothelial cells
What are some benefits to angiogenesis-metronomic therapy?
- Sensitize endothelium to chemotherapy
- Reduce T-cell regulation at malignant site
- Normalizes newly formed vessels
- Works on tumors resistant to chemotherapy
- Reduce production of growth factors
- Low toxicity
Why do most patients die of cancer?
The results of metastases via the lymphatics and/or hematogenous routes
What are the two theories of activation of invasion and metastasis of cancer cells?
- Seed and soil
2. Hemodynamic consideration
How does the seed and soil theory of cancer metastasis work?
An organ will have matching receptors to tumor cells and will host the tumor
How does the hemodynamic consideration theory of cancer metastasis work?
Cancer cells get lodged at capillary beds of rich organs like the liver and lungs where they thrive
What are the phases of metastasis?
- Primary tumor
- Vascularization
- Detachment
- Intravasation
- Circulating tumour cell
- Adhesion to blood vessel wall
- Extravasation
- Growth of secondary tumor
In what cells does lymphoma form in and in what organs does it arise?
Lymphoreticular cells Organs: 1. Lymph nodes 2. Spleen 3. Bone Marrow
What is the signalment for a dog with lymphoma?
6-9 year old Boxer, bull mastiff, basset hound, St. Barnard, Bulldog and Airdale
What are the etiologies of lymphoma?
- Genetic: Gain or loss of chromosomes along with P53 mutation and N-ras
- Infectious factors: Helicobacter
- Environmental factors: 2,4 D, magnetic fields
- Immunosuppression
What are the anatomic classifications of canine lymphoma from most common to least common?
- Multi-centric
- Gastrointestinal
- Mediastinal
- Cutaneous
- Hepatosplenic
What are the ways in which canine lymphoma can be classified?
- Anatomic site
- Extranodal vs. Nodal
- Histologic: Who system
- Grade
- Immunophenotype
What are the grades of lymphoma? What is more common?
Low grade: small cells
Intermediate to high grade: Large cells and lymphoblasts ( more common)
What are the different immunophentotypes of lymphoma? Why are these important? Which is most common?
- B cell (more common)
- T cell
Determine how patient will response to therapy and survive
What can T cell lymphomas in dogs be associated with?
- Hypercalcemia
2. Decreased response and survival time
What are the clinical signs of multicentric LSA in dogs?
- Lymphadenopathy
- Hepatosplenomegally
- Weight loss, anorexia, lethargy, fever if patient is in substage B
Which type of lymphoma is most likely to result in a patient with substage B?
T cell LSA
What are some differentials for lymphadenopathy in dogs?
- Immune mediated disease
- Disseminated infection from virus, bacteria, fungus
- Other forms of neoplasia
What are the clinical signs of GI lymphoma in dogs?
Weight loss and diarrhea from malabsorption
What are the clinical signs of mediastinal lymphoma in dogs?
- Regurgitation
- Hypercalcemia
- PU/PD
- Pre-caval syndrome
- Dyspnea
What is a paraneoplastic syndrome?
Any syndrome associated with cancer but not due to the tumor directly
What are the clinical signs/diagnostic indicators of a dog with paraneoplastic syndrome?
- Anemia (most common)
- Fever
- Thrombocytopenia
- Hypercalcemia ( T cell LSA)
- Monoclonal gammopathies (B cell LSA)
- Cachexia
What types of neoplasia can cause hypercalcemia? Why is it important to check for neoplasia if a dog is hyperalcemic?
- Anal sac carcinomas
- Thyomas
- T cell LSA ( 10-35%)
2/3 case of hypercalcemic dogs have neoplasia
What is the mechanism behind hypercalcemia with neoplasia? Is this the only mechanism?
The tumor increases production of PTHrp
No
How is LSA in dogs diagnosed?
- Fine needle aspirate with cytology and flow cytometry ( most common)
- Biopsy
Why would we do a biopsy in a dog with suspected LSA?
If the FNA can’t confirm the diagnosis, the grade the tumor, and give it a subclassification.
Which lymph node should be avoided when doing a biopsy of LSA? Why?
Mandibular
It drains the mouth and prevents dental disease, plus has a high chance of masking diagnosis due to high cell reactivity.