Onc: Radiation Therapy

Front 1

When should you use CT vs. RT vs. surgery?

Back 1

When both local disease extent and risk of systemic disease are low, use surgery or RT.
When local disease extent is low and risk of systemic disease is high, use CT AND surgery/RT.
When both local disease extent and risk of systemic disease are high, use all three.

Front 2

What does it mean to say that chemotherapy and radiation are synergistic?

Back 2

Chemotherapy given concurrently with the radiation appears to improve the ability of radiation to kill the cancer cells.

Front 3

How is surgery and RT used together?

Back 3

There is a local surgical excision for gross disease with RT for the microscopic disease.
This spares normal tissue function in region of microscopic disease.

Front 4

When is high dose RT used alone, without surgery?

Back 4

Head and neck cancer,
cervical cancer.

Front 5

What is the relationship between tumor grade and stage?

Back 5

Higher grade tumors tend to present at a higher stage.

Front 6

What is the Will Rogers phenomenon?

Back 6

As one introduces improved staging methods, the distribution of patients within each stage of disease will change.

Front 7

What is fractionation?

Back 7

Fractionation is a way of providing

Front 8

What is the difference between x-rays and gamma rays?

Back 8

X-rays are people-made, gamma rays come from nuclear decay.

Front 9

Does all DNA damage come direcly from photons?

Back 9

No; some comes indirectly from free radicals.

Front 10

What are the four R's of fractionated radiation therapy?

Back 10

1. Repair of radiation damage (normal tissues are better able to repair radiation damage in between doses),
2. Redistribution (by alowing the cancer cells to move through the cell cycle during course of treatment, we increase the probability that each cell will be irradiated during a sensitive period),
3. Reoxygenation (hypoxic cells are less sensitive to radiation than well-oxygenated cells,) and
4. Repopulation of tumor cells (negative consequence, growth of tumor during course of fractionated treatment)

Front 11

What are the pros and cons of shortening the course of radiation?

Back 11

Pro: outcome improvement by decreasing repopulation
Con: Some normal tissues have enhanced acute effects from rapid radiation.

Front 12

How does radiation kill cells?

Back 12

Radiation kills cells via DNA strand breaks.

Front 13

Why would you give a smaller dose of radiation?

Back 13

Because smaller doses spare late-responding tissues (normal tissues.)

Front 14

When do you use photons vs. particles?

Back 14

Particles are better for superficial lesions (skin, lymph nodes in neck), while photons are better for deeper targets (lung, abdomen, pelvis.)

Front 15

What is the difference between organs that have serial vs. parallel function?

Back 15

Lesions to organs with serial function cause the entire organ to lose function, lesions to organs with parallel function do not cause the organ to stop working.