WBR0339
| Author | [[PageAuthor::Rim Halaby, M.D. [1] (Reviewed by Alison Leibowitz)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pharmacology |
| Sub Category | SubCategory::Oncology |
| Prompt | [[Prompt::Androstenedione, an androgen formed by theca cells and transported to granulosa cells, is converted to estrogen by the action of enzyme X under the positive hormonal effect of follicle-stimulating hormone (FSH). On enzyme X, FSH's activity is demonstrated to be time- and dose-dependent. The illustration below demonstrates the enzymatic conversion of androstenedione to estrogen. Pharmacologic inhibition of enzyme X is most likely prescribed in which of the following conditions?
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| Answer A | AnswerA::Benign prostate hyperplasia (BPH) |
| Answer A Explanation | AnswerAExp::Patients with BPH are often prescribed alpha-1-antagonists, such as tamsulosin, or 5-alpha-reductase inhibitors, such as finasteride. |
| Answer B | AnswerB::Prostate adenocarcinoma |
| Answer B Explanation | AnswerBExp::Anti-androgens, such as flutamide, are typically prescribed to patients with prostate adenocarcinoma. |
| Answer C | AnswerC::Breast cancer in post-menopausal women |
| Answer C Explanation | [[AnswerCExp::Aromatase inhibitors are often prescribed to post-menopausal women with breast cancer in order to decrease their peripheral production of estrogen.]] |
| Answer D | AnswerD::Contraception |
| Answer D Explanation | AnswerDExp::Hormone replacement therapy, such as administered progestin and estrogen, may be used to aid in contraception. |
| Answer E | AnswerE::Triple negative breast cancer |
| Answer E Explanation | [[AnswerEExp::Patients with triple negative breast cancer, defined as breast cancers that do not express estrogen receptors (ER), progesterone receptors (PR), or Her2/neu, do not benefit from hormonal therapy, such as selective estrogen receptor modulators (SERMs) or aromatase inhibitors.]] |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::The enzyme described above is aromatase. FSH has a time- and dose-dependent mechanism for the activation of aromatase. In granulosa cells, aromatase is responsible for the conversion of androstenedione to estrogen. Inhibition of aromatase by pharmacologic therapy (aromatase inhibitors), such as anastrozole and exemestane, is particularly beneficial for post-menopausal women with breast cancer. In these patients, inhibition of peripheral estrogen production is essential for targeted therapy. Educational Objective: Aromatase, an enzyme stimulated by FSH, is responsible for the conversion of androstenedione to estrogen. Aromatase inhibitors, such as anastrozole and exemestane, are clinically useful in post-menopausal women with breast cancer. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::aromatase, WBRKeyword::inhibitor, WBRKeyword::inhibition, WBRKeyword::anastrozole, WBRKeyword::exemestane, WBRKeyword::postmenopausal, WBRKeyword::post-menopausal, WBRKeyword::menopause, WBRKeyword::breast cancer, WBRKeyword::estrogen, WBRKeyword::androstenedione, WBRKeyword::receptor, WBRKeyword::granulosa cell, WBRKeyword::FSH, WBRKeyword::hormone, WBRKeyword::hormones |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |
