Review Slides Part 3

Question 1

Elevated IFP can cause _________ drug uptake.

Answer 1

decreased

Question 2

Some chemodrugs require ________ for maximal efficiency so hypoxia can cause resistance.

Answer 2

oxygen

Question 3

Low pHe causes ___________ across the plasma membrane which prevents drug delivery for many chemotherapeutic agents.

Answer 3

pH gradient

Question 4

Well-oxygenated cells require _________ of the dose of anoxic cells to achieve a given level of cell killing.

Answer 4

1/3

Question 5

The oxygen enhancement ratio is given by:

Answer 5

OER = (radiation dose in hypoxia) / (radiation dose in air) for the same level of biological effect.

Question 6

The OER for x-rays in most cells is _________. At <3.0 Gy dose, OER is _________. For high LET OER is __________.

Answer 6

2.5 - 3
reduced
1 -1.5

Question 7

The diffusion distance of oxygen in respiring tissue is ____________.

Answer 7

100-180 um

Question 8

Cells beyond diffusion distance become _________, but cells bordering on these regions are _________ although ________.

Answer 8

necrotic
viable
hypoxic

Question 9

Acute and chronic hypoxia can _________ in the same tumor.

Answer 9

coexist

Question 10

Oxic-hypoxic cycles in tumors have been observed to occur with periodicities of ____________.

Answer 10

minutes

Question 11

If reoxygenation occurs between fractions, then the radiation killing of initially hypoxic cells will be _________ and the hypoxic cells have _________ impact on response.

Answer 11

greater
less

Question 12

5 ways to improve tumor oxygenation are:
1. ___________
2. ___________
3. ___________
4. ___________
5. ___________

Answer 12

increasing oxygen-carrying capacity in the blood
anti-vascular endothelial growth factor (VEGF) therapies
decreasing tumor oxygen consumption
mild hyperthermia
inhibitors to block Ras signaling

Question 13

Radiosensitizing properties of oxygen are due to its ____________ so other ___________ might act as sensitizers.

Answer 13

electron affinity
electron-affinic compounds

Question 14

____________ compounds contain members that sensitize hypoxic cells both in vitro and in animal tumors.

Answer 14

nitromidazoles

Question 15

Hypoxic cytotoxins reduce the influence of hypoxia on radiation response using __________ that are toxic under hypoxic conditions.

Answer 15

bioreductive

Question 16

The bioreductive drug ____________ is cytotoxic to hypoxic cells at oxygen concentrations up to ________ uM/L or pO2 _______ mmHg.

Answer 16

tirapazamine (TPZ)
10
6

Question 17

Tirapazamine can combine with chemotherapeutic agent ________ to increase its toxicity. Shown efficacy in lung and H&N cancers.

Answer 17

cisplatin

Question 18

The four Rs of radiobiology are ________, __________, _________, and ________.

Answer 18

repair
repopulation
redistribution
reoxygenation

Question 19

In Repair of sublethal damage, DSB is repaired by enzymes in ________.

Answer 19

hours

Question 20

In Repopulation, cell growth takes _______.

Answer 20

~ week

Question 21

In Redistribution (Reassortment) of cells the cell cycle effect takes ________.

Answer 21

~ day

Question 22

In Reoxygenation the oxygen effect takes _________.

Answer 22

hours to days

Question 23

Dividing dose in number of fractions _________ normal tissues by allowing for _______ and __________ of normal tissue.

Answer 23

spares
repair
repopulation

Question 24

Dividing the dose in number of fractions _________ to tumor through __________ and __________ into radiosensitive phases.

Answer 24

increases damage
reoxygenation
redistribution

Question 25

________ is the regrowth of tumor cells, in humans the delay is ________.

Answer 25

proliferation
4 weeks

Question 26

The extra dose to counter proliferation is only accounted for in _____________ tissues.

Answer 26

early responding

Question 27

The alpha/beta ratio for early responding tissues is ________ and for late responding tissues is ________.

Answer 27

10 Gy
2-3 Gy

Question 28

_______ responding tissues are more sensitive to change in fractionation.

Answer 28

late

Question 29

The dominant factor in determining late effects is ___________.

Answer 29

fraction size

Question 30

The major problems with chemotherapy are _________ such as gut, kidney and bone marrow, and ___________.

Answer 30

toxicity to normal tissues
intrinsic and developed drug resistance

Question 31

___________ is a drug that binds to EGFR, inhibiting cell growth, inducting apoptosis and decreasing matrix metalloproteinase and VEGF.

Answer 31

Cetuximab

Question 32

__________ is a chemotherapy drug that induces normalization of vessels in tumor and makes them more response to cytotoxic chemo and RT.

Answer 32

Bevacizumab

Question 33

Photodynamic therapy uses ___________ and __________.

Answer 33

photosensitizing agent
particular type of light

Question 34

When photosensitizers in PDT are exposed to a specific wavelength of light, they produce a form of __________ that ______ nearby cells.

Answer 34

oxygen
kills