Oncology and Hematology Flashcards
What mutation is a concern in Collie-type breeds?
ABCB1 (mut/mut) phenotype
Name several alkalyating agents?
Chlorambucil (Leukran) Cyclophosphamide (Cytoxan) CCNU (Lomustine) Melphalan (Alkeran) Dacarbazine (DTIC) Ifosfamide (Ifexx) Nitrogen Mustard (Mustargen)
What is the MOA of alkylating agents?
They bind to DNA strands, insert alklyl group and inhibit protein synthesis
Chlorambucil
Cyclophosphamide
CCNU (Lomustine)
What drug can be substituted for cytoxan if hemorrhagic cystitis occurs?
Chlorambucil (Leukran)
Which alkylating agent can result in hemorrhagic cystitis?
Cyclophosphamide (Cytoxan)
Which alkylating agent can result in hepatotoxicity?
CNNU (Lomustine) = Give with Denamarin
What is the MOA of vinca alkaloids?
Plant alkaloids bind to microtubules to prevent normal formation and function of mitotic spindles, thus arresting cell division in metaphase (CELL cycle specific)
Name 3 plant alkaloids.
Vincristine
Vinblastine
Vinorelbine
What is the MOA of antimetabolite drugs?
Interfere with biosynthesis of nucleic acids by substituting them for normal metabolites and inhibiting normal enzymatic reactions
Name 5 antimetabolites.
Methotrexate Fluorouracil (5-FU) Gemcitabine Cytarabine (Cytosar) Hydroxyurea
What is the MOA of DNA cross-linker?
Binding within and between DNA strands and thus inhibiting protein synthesis in cell-cycle nonspecific manner
Name 2 DNA cross-linkers.
Carboplatin
Cisplatin
Why can cisplatin not be used in cats?
CISPLAT = SPLATS CATS
Causes severe pulmonary edema
What is the MOA of antitumor antibiotics?
Inhibition of toposiomerase II DNA synthesis (S phase specific) = Inhibitis DNA synthesis
Which medication can be given with doxorubicin to reduce cardiotoxicity?
Zinecard
Name several antitumor antibiotics?
Doxorubicin
Mitoxantrone
Acrinomycin D
Bleomycin
What is DIC?
Disseminated intravascular coagulation (DIC) → systemic microthrombosis can progress to life-threatening hemorrhage
What are the 4 steps in the pathogenesis of DIC?
- ↑ thrombin production
- Suppression of physiologic anticoagulant pathways
- Impaired fibrinolysis
- Activation of inflammatory pathways
When are tissue factor be expressed?
Monocytes and endothelial cells, circulating during inflammation and on cancer cells
What is the main stimulus for thrombin formation in DIC?
Tissue Fator: VIIa complex (extrinsic pathway)
When does bleeding and hypercaoguable occur during DIC?
Hypercoagulable condition occurs early in the course of DIC and bleeding associated with prolongation of coagulation times occurs later in the course § Consequence of coagulation activation, platelets, coagulation factors, and anticoagulants are consumed, degraded, and/or inhibited
§ Transition from accelerated coagulation to consumption of coagulants and anticoagulants corresponds with the clinical consequences of microthrombosis and vascular occlusion followed by uncontrolled hemorrhage
§ Combos of coagulation-anticoagulation-fibrinolytic-inflammatory derangements exist (depend on underlying cause and coexisting dzs)
What are the 5 general things that are associated with DIC and aid in diagnosis?
o Prolongation of coagulation times
o Reduction in platelet numbers
o Elevation of D-dimer or soluble fibrin
o Decrease in AT activity
o Clinical or postmortem evidence of thrombosis
What test in dogs can exclude DIC as diagnosis, with 95% confidence?
Negative D-dimer test
What are the 4 main goals in treating DIC?
Promoting capillary blood flow, eliminating underlying cause, supporting target organs, replacement therapy, and anticoagulants
What is the MOA of aspirin?
Nonreversible thromboxane-2 inhibitor that decrease platelet aggregation/adhesion
What is the MOA of heparin?
§ Glycosaminoglycan that exerts antithrombotic effect by binding to and potentiating the inhibitory actions of AT on thrombin and factors IXa, Xa, XIa, and TF:VIIa
What forms the hemostatic plug?
Platelet aggregates stabilized by generation of thrombin-mediated platelet fibrin meshwork, trapping PLT and RBCs
Which platelet receptor is important for fibrinogen, fibronectin, and vWF to bind?
GPIIb/IIIa
What 3 things does a BMBT allow you to assess?
Thrombocytopenia, platelet dysfunction, vWD
Which breeds get Glanzmann thrombasthenia?
Otter hound and Great Pyrenees
Abnormal adhesion and clot retraction, aggregation failure, reduced or absent GPIIb/IIIa
What is Chediak Higashi syndrome and which breed gets it?
Persian cats. Lack of dense granules, secretion failure, abnormal platelet aggregation
Name 3 blood products that can supply ACTIVE platelets?
Fresh whole blood, platelet rich plasma, platelet concentrate
What is posttransfusion purpura?
Immune thrombocytopenia in a recipient due to development of high titer alloantibodies that cross-react with the recipients’ platelet antigens
What is a Phase I clinical trial?
Toxicity dose finding
What is a Phase II clinical trial?
Efficacy and responding histologies
What is a Phase III clinical trial?
Comparison to standard of care
What is the suggested percentages of dogs undergoing chemo that will need dose reduction, get life-threatening toxicity, and will die?
Less than 20% need dose reduction (due to hospitalization or severe neutropenia), less than 5% have life-threatening toxicity, less than 1% reis of treatment-related mortality
What is the traditional dosing for chemotherapy?
Based on metabolic body size, body surface area, m2 (smaller animals have high metabolic rate = higher dose)
Which chemo can have cumulative thrombocytopenia?
CCNU
Which chemo can have cumulative cardiotoxicity effects leading to irreversible DCM and CHF and what is the cumulative dose?
Doxorubicin
Cumulative dose above 180 mg/m2
What results in cyclophosphamide resulting in hemorrhagic cystitis?
Metabolite acrolein
Thus give with lasix
Which chemo has irrversible hepatotoxicity?
CCNU
What is a benefit and drawback of pegylated liposomal doxorubicin?
Less cardiotoxicity and myleosuppression, BUT cutaneous toxocity = Palmar and plantar erythrodysesthesia syndrome (mild crusting to severe ulceration)
Which vinca alkaloid is thought to concentrate in lung tissue?
Vinorelbine
Which antimetabolite has been used as a radio-sensitizer?
Gemcitabine
What are the 2 types of radiation therapy that can be used?
· Particulate: has mass and include electrons, protons, neutrons
· Electromagnetic: no mass, made of photons including X-rays and γ-rays
How does radiation work for neoplasia?
· Direct action occurs when photon strikes electron knocking it off creating positive ion. Electron then causes DNA damage. (1/3 of the time)
· Indirect action occurs when electron interacts with water near DNA creating free radicals, which then damage DNA. (2/3 of the time). Oxygen must be present.
· Damage is single- and double-strand breaks of DNA. Single-strand breaks are common, but can be repaired. Double-strand breaks occur more rarely, but usually result in cell death.
How many hours are required for normal tissue to repair single-strand breaks?
About 6 hours
What is fractionation with radiation therapy?
§ Fractionation, delivery of multiple doses of radiation at intervals that allow normal tissues time to repair DNA damage. Each single dose kills the same percent of cells each time, therefore unlikely one large dose is sufficient to kill all tumor cells.
What is a gray?
1 J of energy deposited into 1 kg of mass
What are the acute side effects of radiation?
due to death of stem cell population. Inflammation, ulceration, mucositis, desquamation. These usually resolve in 2 to 3 weeks following treatment. Must provide hydration and nutrition if oral cavity involved.
What are the late side effects of radiation?
slowly proliferating tissues. Endothelial and parenchymal cells die later, these effects permanent. Examples: bowel stricture, cataracts, demyelinating myelopathy, osteonecrosis, KCS, skin fibrosis. Larger doses result in more late effects.
What is the route that soft tissue sarcomas like to met?
Hematogenously
Which tumor can Spirocerca lupi be associated with?
Soft Tissue Sarcomas
For soft tissue sarcomas with incomplete margins what is the recurrence rate in 1 year?
60%
10X more likely to recur with incomplete excision
What factors are associated with survival for soft tissue sarcomas?
Mitotic rate (>20 MF/HPF = 2.6 x more likely to die) Tumor necrosis (>10% necrosis = 2.8X more likely to die) Size, completeness of excision, degree of differentiation, grade, local control
What is the classic signalment for hemangiosarcoma?
Median age of 10 yrs
GSD, Goldens, Labs