Devita, Hellman, and Rosenberg's Cancer

LWBK1006-07 LWW-Govindan-Review November 22, 2011 13:54

Chapter 7•Principles of Radiation Oncology 87

Question 7.9. Which of the following statements describes the role of oxygen in radia-

tion effects?

A. A greater dose of radiation is required for cell killing in an oxic con-

dition compared with a hypoxic condition.

B. A randomized trial showed that epoetin b improved survival in

patients with head and neck cancer.

C. Oxygen need not be present at the time of irradiation for oxygen

enhancement of radiotherapy to occur.

D. Hyperbaric oxygen often shows a dramatic increase in curability with

standard fractionated radiotherapy.

E. The oxygen enhancement ratio (OER) has more relevance on the

exponential portion of the cell survival curve.

Question 7.10. Which of the following best describes the concept of altered fractionation?

A. Accelerated fractionation does not reduce the overall treatment time.

B. Hyperfractionation refers to a radiotherapy schedule that uses mul-

tiple daily treatments more than 6 hours apart with reduced fraction

size and increased number of fractions.

C. A Radiation Therapy Oncology Group (RTOG) 9003 randomized

trial showed that standard fractionation treatment was superior to

hyperfractionation and accelerated fractionation with concomitant

boost used for advanced head and neck squamous cell carcinomas.

D. Continuous hyperfractionated accelerated radiation therapy (CHART)

gives a higher total dose than the standard fractionated treatment.

Question 7.11. Which of the following statements regarding interaction of chemotherapy

and radiation therapy is NOT true?

A. Rationale for combining radiation therapy with radiosensitizing

chemotherapy is primarily to confer an additive effect.

B. Gemcitabine is a potent radiosensitizer, however, when used concur-

rently with radiation therapy, radiation fields, and gemcitabine dose

and scheduling must be carefully defined, as noted in experiences with

pancreatic cancer clinical studies.

C. Paclitaxel in combination with radiation has demonstrated clinical

benefits in treatment of locally advanced lung cancer

D. Mechanism of radiosensitization by cisplatin may be due to its abil-

ity to inhibit DNA repair of radiation induced DNA double-strand

breaks.

Question 7.12. Which of the following statements is NOT true regarding modulation of

radiation by hyperthermia?

A. Localized heat treatment can be delivered with microwaves, ultra-

sound, or radiofrequency sources of energy.

B. The lethality of hyperthermia is thought to be in part from denatu-

ration of proteins.

C. Similar to radiation-induced kill, lethality from heat is most pro-

nounced when cells are in the G2/M phase.

D. The temperature 42.5◦C seems to be critical, with small increments

above this temperature leading to a steep increase in lethality.