module 17

Question 1

what happens during the G0 phase of the cell cycle?

Answer 1

resting, cells dont replicate

Question 2

what happens during the G1 phase of the cell cycle?

Answer 2

cell prepares to synthesize DNA

Question 3

what happens during the S phase of the cell cycle?

Answer 3

cell synthesizes DNA

Question 4

what happens during the G2 phase of the cell cycle?

Answer 4

cell prepares for mitosis

Question 5

what happens during the M phase of the cell cycle?

Answer 5

cell divides - mitosis

Question 6

what cells are hardest to treat in chemotherapy (phase of cell cycle) and why

Answer 6

G0 - because most of chemo drugs target proliferation and these cells are at rest

Question 7

what are obstacles to sucessful chemotherapy?

Answer 7

1. toxicity to normal cells
2. achieving 100% cell kill
3. difficult early detection
4. solid tumors
5. drug resistance

Question 8

why does cancer treatment cause toxicity to normal cells?

Answer 8

because cancer cells are very similar to normal cells, making it more difficult to target cancer cells

Question 9

what kind of cells are most affects by cellular toxicity

Answer 9

cells with high proliferation fraction - GI epithelium, hair follicles, germinal epithelium of the testes, bone marrow

Question 10

why is 100% cell kill hard to reach

Answer 10

-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)

Question 11

why is early detection difficult?

Answer 11

-a lot of cancer cells before client experiences symptoms
-caught late then there is a slow progression to death (better than worse)

Question 12

at what age should you start mammograms and at what interval

Answer 12

-50yrs old
-2-3 years and earlier for those with history

Question 13

how often should a women get a pap test?

Answer 13

every year but if 3 tests come back without concern, then every 3 years

Question 14

what is the screening protocol for people not at risk for colon cancer

Answer 14

test over 50 should have a fecal blood test every 2 years

Question 15

what the screening colonoscopy for high risk patients?

Answer 15

every 5 years have a colonoscopy

Question 16

what is the screening protocol for prostate cancer?

Answer 16

men over 50 should have a digital rectal exam and or a PSA blood test

Question 17

why dont solid tumors react well to cancer treatment?

Answer 17

the inner most cells of tumors are in the G0 phase and drugs dont target these cells

Question 18

explain the mechanisms of drug resistance

Answer 18

1. decrease drug uptake
2. increased drug efflux
3. decreased drug activation (prodrugs)
4. reduced target sensistivity and increased cellular repair
5. decreased apoptosis

Question 19

how does increased drug efflux work with chemo drugs

Answer 19

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

Question 20

what is intermittent chemotherapy?

Answer 20

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

Question 21

what is combination chemotherapy?

Answer 21

using more than one drug is more effective than a singular agent

Question 22

why is combination therapy more effective

Answer 22

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

Question 23

what are common toxicity from chemotherapy

Answer 23

typically occurs in cells with high growth fraction
1. digestive tract injury
2. bone marrow toxicity
3. nauesea and vomitting