482 Obstetrics and Gynecology Board Review •••
❍ Describe phase I, II, and III studies.
Phase I studies determine the toxicities and maximally tolerated dose of a therapeutic agent in humans.
Phase II studies are used to obtain efficacy of an agent in order to determine whether further study is advised.
Phase III studies are a randomized controlled trial with the purpose of comparing the efficacy of an investigational
agent to a standard therapy.
❍ When used as a radiosensitizer, 5-fluorouracil frequently exacerbates what side effect of radiation therapy?
Diarrhea, which is a common side effect of both therapies.
❍ Why is intravenous etoposide administered slowly?
To prevent hypotension.
❍ What agent can be used with ifosfamide to minimize the risk of hemorrhagic cystitis?
Mesna (2-mercaptoethanesulfonate).
❍ What parameters are used to calculate body surface area?
Height and weight (BSA = SQRT [ht.wt/3600]).
❍ Why does tumor heterogeneity often result in drug resistance?
Spontaneous mutations give rise to small numbers of resistant cells that may rapidly reproduce when sensitive cells
are killed.
❍ What is the multidrug resistance (MDR) gene?
The MDR gene is normally present in some human tissues and may be activated in tumors by exposure to certain
chemotherapeutic agents, resulting in resistance to many drugs.
❍ Adriamycin-associated cardiotoxicity may be anticipated by the use of what imaging study?
MUGA scan to estimate ejection fraction at baseline and after every 2 to 3 cycles of treatment.
❍ Tamoxifen is used to antagonize the effect of estrogen on breast cancer, yet may induce endometrial bleeding
and cancer. Why?
Tamoxifen is a mixed estrogen agonist/antagonist, depending on the target tissue.
❍ How long should high-dose progestins be used in patients with recurrent endometrial cancer to obtain
maximum clinical response?
At least 3 months.
❍ What is the most important factor for predicting the efficacy of progestin therapy in endometrial cancer?
Progesterone receptor status of the tumor.
❍ Marinol (tetrahydrocannabinol) should be used as an antiemetic with caution in what age group?
Elderly patients may experience dysphoria with the use of Marinol.