Cancer Therapy Basics

Exam 1 Study Guide Cancer Therapy Basics ● ● ● ● Which lab result shows a drop in immunity during chemotherapy? ○ CBC (neutrophils ---neutropenia, platelet count -- thrombocytopenia, anemia --- drop in RBC, WBC) Chemoreceptor trigger zone & drug therapy ○ Many anticancer drugs care moderate to severe N/v by stimulating the chemoreceptor trigger zone ○ Drug therapy is most common treatment for DISSEMINATED cancers (leukemia, disseminated lymphomas, metastases) and other local cancers ○ Drug therapy is important when working alongside (adjunct) to surgery or radiation. It suppresses or kills malignant cells left behind by surgery or radiation. It can reduce recurrence and improve survival Goals/principles of combination therapy. ○ Combination therapy is more effective than single drug therapy ---- pts are usually treated w/ at least 2 drugs ○ Benefits: ■ (1) suppression of drug resistance ■ (2) increased cancer cell kill ■ (3) reduced injury to normal cells (at any given level of anticancer effect) ○ Suppression of drug resistance ■ Drug resistance occurs less frequently with combo therapy than single drug therapy ○ Increased cancer cell kill ■ Administering multiple drugs w/ all different mechanisms of actions are more likely to kill more malignant cells than single drug therapy ■ Greater cell kill is especially likely if a drug-resistant subpopulation of cells is present. ○ Reduced injury to normal cells ■ By using a combination of drugs that do not have overlapping toxicities, we can achieve a greater anticancer effect than we could safely achieve using any of the agents alone ■ Table 105.6 ---- two different drugs w/ different levels of toxicity but don’t overlap so toxicity is at a tolerable level ○ Guidelines for drug selection ■ (1) Each drug should be effective by itself ■ (2) each drug should have a different mechanism of action ■ (3) the drugs should have minimally overlapping toxicities Are chemotherapy regimens given in cycles or continuously? Why? ○ Intermittent chemotherapy: ■ Goal of chemo is to produce 100% kill of neoplastic cells while causing limited injury to normal tissues (especially in bone marrow and GI epithelium) ■ Is primary technique for achieving ^ goal ■ When cytotoxic anticancer drugs are administered intermittently, normal cells have time to repopulate between rounds of therapy --- HOWEVER TO BE SUCCESSFUL NORMAL CELLS MUST REPOPULATE QUICKER THAN MALIGNANT CELLS Principles of Antimicrobial Therapy ● ● ● Resistance: How does this occur and what are the signs of it? ○ Occurs by spontaneous mutation, conjugation, inactivation of a drug, decrease concentration of drug at active site, produce drug antagonist, alter structure of drug target molecules Difference between empirical treatment and culture & sensitivity treatment? Why do we have both? ○ Empirical treatment is an educated guess based on symptoms that a patient presents with, it is employed before receiving the results from a culture and sensitivity treatment. Culture and sensitivity treatment is a targeted antibiotic based on the results of a culture. We use both methods because while we wait for the cultures to come back, we do not want to allow a patient to become more ill thus we employ empirical therapy in the meantime. Uses for a first-generation cephalosporin ○ Used as a prophylactic drug before surgery Antibacterials ● ● ● Penicillins ○ Most common antibiotic ○ Most common adverse effect is ANAPHYLAXIS ○ Beta-lactum ring that makes resistance higher ○ VANCOMYCIN ■ Used for CDIFF and MRSA infections ■ Primary adverse effect is nephrotoxcity ■ Red man syndrome Tetracyclines ○ Can cause discoloration of teeth in children < 8 and pregnant women ○ Contradicted with food or calcium, mg, laxatives containing mg ○ Adverse effects: renal and liver toxicity, phototoxicity ○ Used for anthrax, risketal diseases, chlamydia, acne, gonnrrhea ○ Doxycycline: ■ Can be used to treat cholorquine resistant forms of malaria Macrolides ○ Erythromycin ■ Alternative to penicillin G ■ First line for whooping cough, diphtheria, urethritis, and cervicitis ■ Principal adverse effect: QT prolongation ● Trimethoprim-sulfamethoxazole ○ Bactrim ○ Used primarily for treatment of UTIs ○ Principal adverse effect is SJS “red man syndrome”, hemolytic anemia, hypersensitivity rxns, kernicterus (neuro defect) Antimycobacterial ● ● ● ● ● ● DOT ○ Direct observation therapy- watching the patient take the med ○ Helps with patient adherence ○ Can also help nurse identify any adverse effects Isoniazid: ○ 1st line drug choice for TB and can be used for prophylaxis to TB ○ Bactericidal ○ MAIN ADVERSE EFFECTS: HEPATOTOXICITY, PERIPHERAL NEUROPATHY ○ Peripheral neuropathy can be limited by ordering vitamin b6 pyroidine ○ Monitor AST and ALTs ○ Contraindicated: ppl w/ hepatitis, hypersensitivity, acute liver disease Rifampin: ○ 1st line drug choice for TB --- DRUG OF CHOICE FOR PULMONARY TB ○ Bactericidal ○ MAIN ADVERSE EFFECTS: HEPATOTOXICITY, discoloration of body fluid red-orange color (urine, tears, sweat, saliva) ○ Monitor AST and ALTs ○ Contraindicated: warfarin, oral contraceptives, certain HIV meds Pyrazinamide ○ 1st line drug choice for TB ○ Bactericidal ○ MAIN ADVERSE EFFECTS: HEPATOTOXICITY, photosensitivity ○ Monitor AST and ALTs ○ Contraindicated: liver impairment Ethambutol ○ 1st line drug choice for TB ○ Bacteriostatic -- impairs cell wall synthesis ○ MAIN ADVERSE EFFECTS: optic neuritis, blurred vision ○ Assess color and visual acuity prior to treatment ○ Contraindicated: optic neuritis Latent versus active TB ○ Latent infection: progression of infection has stopped and no symptoms are present but patient will have bacteria lifelong unless drugs given are given to eliminate dormant bacteria --- dormant bacteria can become active again ○ Active tb uses all four drugs for short period and Latent uses one of 4 drugs for a longer time ○ Get blood test to test for latent TB