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