Oncology Tx Flashcards
Local therapies
Sx
Radiation therapy (medicine oncologist)
Systemic therapies
Chemotherapy (cytotoxic, metronomic)
Immunotherapy (ibs and mabs)
Oncologic surgical principles
Cover ulcerated tissues
Occlude veins
Don’t handle tumor
Plan 3 ways to close
Don’t remove mass based on closure
No drains
Mohs procedure/ stains
Planned margins in benign tumors
Narrow or marginal excision (curative)
High grade tumors
2-3 cm, high recurrence (75%), follow-up procedures
Feline injection site sarcomas
5 cm margins/ 2 facial planes deep (muscle fascia)
Marginal excision
Diameter of tumor laterally
One fascial plane deep
Surgical doses
Radical (remove tumor completely), wide margins, marginal excision, cytoreductive (debulking)
Influenced by size, location, metastasis
What can you glean from the histopathology report?
Grade, margins, mitosis rate/index, vascular invasion/embolus
Does laser applied to the tumor bed influence recurrence?
No it’s not helpful
What are the 2 types of radiation?
Brachytherapy particles: travel short distances (Strotium-90, iridium-192, iodine-131)
Teletherapy: linear accelerator (rays, electrons)
How does radiation kill cells
Fractionation: split dose into multiples over time, kills cancer cells while allowing normal tissue to recover
1/3 direct damage to DNA, 2/3 indirect free radical damage
Why are the 4 R’s of radiation?
Repair, repopulation, reassortment, reoxygenation
Repair
Repair DNA damage within 6 hours (some need more)
Allows abnormal tissue to recover
Tumor cells also repair damage and proliferate
Repopulation
Proliferation surviving clomogenic tumor cells
Cancer cells become more sensitive in M and G2
2nd dose may capture radioresistant cells as they become more sensitive
Reoxygenation
O2 required to generate free radicals
As tumor cells die, expose new areas to oxygen (next dose may treat reoxygenated cancer cells)
Conventional RT
For microscopic dz
Acute side effects
Advantage: long- term dz control
Disadvantages: multiple anesthesias and long tx course
Palliative RT
For macroscopic dz
Late side effects
Advantage: short tx course, fewer anesthesias, few side effects
Disadvantage: shorter dz control, possible late side effects
Stereotactic RT
For macroscopic dz
Late side effects
Advantages: durable palliation
Disadvantages: uncertain long term outcome, possible late side effects
Acute side effects of radiation
Rapidly diving cells (epithelial, GI, skin, hair follicles, BM)
Reversible
2-4w to develop and heal
Reflective of total RT dose
Chronic effects of RT
Slowly dividing tissues (bone, muscle, BVs), nervous, heart, lungs)
Irreversible loss of function —> fibrosis and necrosis
6m-years to develop
Reflective of large fraction size
How are acute side effects of RT managed?
Prevent self trauma
Pain management
Tea- tannic acid
Anti inflammatories/ prednisone
Silver sulfadiazine
How are chronic side effects of RT managed?
Surgical removal
No tx possible
Indications of cytotoxic chemotherapy
Sensitive tumor type (round cells)
Systemic dz/ already has mets
High chance of mets
Gompertzian growth curve
A mathematical model that describes the growth of cancer tumors
Exponential growth: RT + chemo work best
Surgery growth curve to the left back to exponential growth
Cell cycle specific drugs
Targets tumor in a specific time of cell cycle
Base analogues , folate inhibitors, tubule inhibitors
Cell cycle non-specific
Targets DNA in any part of the cell cycle
Alkylators, heavy metals, abx
What is the most common chemotherapy side effect
BM neutropenia
Alopecia
GI (anorexia, nausea, V/D)
Doxorubicin
Anti tumor Abx
Effects: cardiac necrosis, GI upset, neutropenia, tissue necrosis with extravasation, mast cell degranulation, alopecia/ hair thinning/ skin darkening, radiation recall
Mitoxanthrone
Anti tumor abx
Effects: BM suppression, GI toxicity, blue color urine
Mechlorethamine
Not used in practice , spontaneous gases
Cyclophosphamide
Alkylating agents, must be activated in the liver
Side effects: marrow-sparing a role in cause sterile hemorrhagic cystitis, GI, alopecia, pulmonary fibrosis
Chlorambucil
Alkylating agent
Platelets affected more often with chronic use of
CCNU
Severely marrow suppressive 1-3w
Liver toxicity (give denamarin too)
Melphalan
Idiosyncratic effect: Pulmonary fibrosis
DTIC/ temozolamide
Side effects: GI, Vesicant
Vincristine
Tubule inhibitors
Marrow suppression
Peripheral neuropathy ileus, vesicant
Vinblastine
Tubule inhibitors
Side effects: more marrow suppressive, less neuropathy, sub for ileus, vesicant
Cisplatin
Heavy metal alkylators
Effects: renal/ diuresis, vomiting, moderate marrow suppression, splats cats
Carboplatin
More marrow suppressive (cumulative)
Neurotoxic
Rabacfosadine
Effects: pulmonary fibrosis after 5th dose, dermatopathy
Contrain: WHWT
NSAIDS
Piroxicam, carprofen, deramax, meloxicam, previcox
Effects: GI, renal
Prednisone
Side effects: panting, laxity, hepatomegaly, alopecia, thin skin, polyphagia, PU/PD
L-asparaginase
Side effects: anaphylaxis (Benadryl), pancreatitis, no marrow suppression
How to manage neutropenia patients
Sterile IV catheter, IV fluids
Broad spectrum abx (no baytril)
Antiematics, appetite stimulants, GI protectants
Usually recover 12-48 hrs
How do you keep your workers safe when handling toxic agents?
Hood or BSC
PPE (gowns, gloves, eye/ face shields)
How do you keep owners safe from exposure to chemotherapy agents?
Avoid urine and feces 48-72 hrs post chemo
Drug compounding
Piling cats
Well placed catheter
