Radiation and chemotherapy Flashcards
Therapeutic ratio
Therapeutic effect of radiation on tumor vs normal tissue toxicity
Fractionation
Use of small doses of ionizing radiation over time (interval between doses allows for normal cell repair of sublethal damage)
Dose-rate
Rate at which ionizing radiation is administered in a single fractionation (lower means more capacity for cells to repair sublethal injury)
Compton scatter
Primary means of interaction in modern RT; incident photon interacts with outer shell electrons resulting in ejection from the atom and further interaction with other atoms
Logrhythmic cell death
Chemo is thought to kill tumor cells by first order kinetics, ie. a fraction rather than a number of tumor cells
How many tumor cells can be detectable if achieving prolonged survival or cure
<10,000
Alopecia
Alkylating agents, plant alkaloids, most antimetabolites (NOT platinum)
Peripheral neuropathy
Taxol, platinum agents, ifosphamide, cyclofosphamide
CNS neuropathy
Ifosphamide, cyclofosphamide
Cardiac dysrhythmia
Taxol, doxorubicin
Cardiomyopathy
Doxorubicin (less likely with doxil)
Hypersensitvity
Taxol, platinum (less common)
Pulmonary fibrosis
Bleomycin
Renal toxicity
Platinum (cisplatin worse)
Hemorrhagic cystitis
Ifosphamide, cyclophosphamide
Vessicants
Antitumor abx, antimetabolites
Palmar plantar erythrodysthesia (PPE)
Doxil
Radiation recall
Doxorubicin, actinomycin D
Mucositis
Anti-tumor abx, antimetabolites
Premature ovarian failure
Alkylating agents (cyclophosphamide, cisplatin, doxorubicin, bleomycin)
Mechanism of paclitaxel (Taxol)
Stabilization of microtubule apparatus
Mechanism of cisplatin
Forms DNA adducts, single and double strand DNA breaks
Mechanism of carboplatin
Forms DNA adducts, single and double strand DNA breaks
Cisplatin vs carboplatin
Cisplatin more nephro- and neuro-toxic, emetogenic; carboplatin causes myelosuppression, less other side effects
Mechanism of liposomal doxorubicin (doxil) = antitumor antibiotic
Intercalation into DNA strand, free radical formation, inhibits topoisomerase I
Mechanism of topotecan
Inhibits topoisomerase I
Mechanism of gemcitabine (Gemzar)
Inserts into DNA as fraudulent base pair
Mechanism of bevacizumab (Avastin)
Recombinant humanized monoclonal antibody that targets VEGF (inhibits angiogenesis)
Side effects of bevacizumab
Proteinuria, HTN, wound healing problems
Mechanism of olaparib (Lynparza)
PARP inhibitor (PARP normal involved in DNA repair)
Indication for olaparib
BRCA 1 or 2 ovarian cancer already treated with 3 courses of chemo
Mechanism of doxorubicin (Adriamycin) = antitumor antibiotic
Intercalation into DNA strand, free radical formation, inhibits topoisomerase I
Side effects of doxorubicin
Myelosuppression, cardiotoxicity (cardiomyopathy, pericarditis-myocarditis syndrome)
Mechanism of ifosphamide
DNA cross-linking, formation of DNA adducts
Side effects of ifosphamide
Myelosuppression, hemorrhagic cystitis, neurotoxicity, SIADH
Most common chemo of chemo RT regimens
Cisplatin
Side effects of cisplatin
Nephrotoxicity, ototoxicity, neurotoxicity, emesis
Mechanism of methotrexate
Binds dihydrofolate reductase
Mechanism of actinomycin D
Intercalates into DNA strands
Mechanism of cyclophosphamide
DNA cross-linking, formation of DNA adducts
Mechanism of etoposide
Inhibits topoisomerase II causing DNA strand breaks
Late effect of etoposide
AML and myelodysplasia
Mechanism of vincristine
Binds tubulin to prevent microtubule assembly
Mechanism of bleomycin
Produces free radicals