module 17 Flashcards
what happens during the G0 phase of the cell cycle?
resting, cells dont replicate
what happens during the G1 phase of the cell cycle?
cell prepares to synthesize DNA
what happens during the S phase of the cell cycle?
cell synthesizes DNA
what happens during the G2 phase of the cell cycle?
cell prepares for mitosis
what happens during the M phase of the cell cycle?
cell divides - mitosis
what cells are hardest to treat in chemotherapy (phase of cell cycle) and why
G0 - because most of chemo drugs target proliferation and these cells are at rest
what are obstacles to sucessful chemotherapy?
- toxicity to normal cells
- achieving 100% cell kill
- difficult early detection
- solid tumors
- drug resistance
why does cancer treatment cause toxicity to normal cells?
because cancer cells are very similar to normal cells, making it more difficult to target cancer cells
what kind of cells are most affects by cellular toxicity
cells with high proliferation fraction - GI epithelium, hair follicles, germinal epithelium of the testes, bone marrow
why is 100% cell kill hard to reach
-no good tests to determine if cancer cells are present in small numbers
-kinetics of cell death with chemo are first (constant percentage of cells killed over time)
why is early detection difficult?
-a lot of cancer cells before client experiences symptoms
-caught late then there is a slow progression to death (better than worse)
at what age should you start mammograms and at what interval
-50yrs old
-2-3 years and earlier for those with history
how often should a women get a pap test?
every year but if 3 tests come back without concern, then every 3 years
what is the screening protocol for people not at risk for colon cancer
test over 50 should have a fecal blood test every 2 years
what the screening colonoscopy for high risk patients?
every 5 years have a colonoscopy
what is the screening protocol for prostate cancer?
men over 50 should have a digital rectal exam and or a PSA blood test
why dont solid tumors react well to cancer treatment?
the inner most cells of tumors are in the G0 phase and drugs dont target these cells
explain the mechanisms of drug resistance
- decrease drug uptake
- increased drug efflux
- decreased drug activation (prodrugs)
- reduced target sensistivity and increased cellular repair
- decreased apoptosis
how does increased drug efflux work with chemo drugs
p glycoprotein is an efflux pump that pumps drugs out the cell - by not allowing the accumulation of drugs in the cell - drug resistance occurs
what is intermittent chemotherapy?
strategy is to kill cancers cells and then allowing normal cells time to recover
for this approach to be sucessful, normal cells must grow back faster than cancerous
what is combination chemotherapy?
using more than one drug is more effective than a singular agent
why is combination therapy more effective
decreased resistance - resistance may be aqucuired due to random mutations in cancer cells. its unlikey tht cancer cells will undergo many mutations - therefore using multiple drugs with different mechanisms will make therapy less effected by resistance
increased cancer cell death- drugs with different mechanisms of action will kill more cancer cells than a single agent
decreased injury to normal cells - using drugs that dont have overlapping toxicities allows us to achieve greater anti cancer effects safely
what are common toxicity from chemotherapy
typically occurs in cells with high growth fraction
1. digestive tract injury
2. bone marrow toxicity
3. nauesea and vomitting
