Master the board step 3

Master the Boards: USMLE Step 3
Tamoxifen is an estrogen receptor antagonist in the breast tissue. It acts as an
endometrial agonist.
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Agonist drugs bind to and activate a receptor. Agonists cause an action.
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Antagonists are drugs with high affinity (bind to receptors well) but no
efficacy (do not make the receptors work). Antagonists block an action.
Invasive Breast Diseases
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Invasive ductal carcinoma is the most common form of breast cancer (85
percent of all cases). It is unilateral. It metastasizes to bone, liver, and brain.
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Invasive lobular carcinoma accounts for 10 percent of breast carcinomas. It
tends to be multifocal (within the same breast) and is bilateral in 20 percent
of cases.
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Inflammatory breast cancer is uncommon, grows rapidly, and metastasizes
early. Look for a red, swollen, and warm breast and pitted, edematous skin
(classic peau d’orange appearance).
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Paget’s disease of the breast/nipple presents with a pruritic, erythematous,
scaly nipple lesion. It’s often confused with dermatosis-like eczema or psoriasis.
Look for an inverted nipple or discharge.
Established risk factors for breast cancer:
Breast cancer screening
guidelines per the U.S.
Preventive Services Task
Force (USPSTF):
• Mammogram every 1–2
years recommended for
ages 50–74.
• Screening before
age 50 is no longer
routinely recommended.
Women < 50 should
only consider
mammographic
screening based on high
individual risk for early
onset breast cancer.
• Teaching breast-self
exam is no longer
encouraged.
• Clinical breast exams
are no longer routinely
advised.
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Age ≥ 50 years old
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Familial BRCA1/BRCA2 mutation carrier
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Exposure to ionizing radiation
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First childbirth after age 30 or nulliparity
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History of breast cancer
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History of breast cancer in a first-degree relative
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Hormone therapy
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Obesity (BMI ≥ 30 kg per m 2 )
When are BRCA1 and BRCA2 gene testing indicated?
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Family history of early-onset (< 50 years of age) breast cancer or ovarian cancer
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Breast and/or ovarian cancer in the same patient
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Family history of male breast cancer
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Ashkenazi Jewish heritage
Treatment
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Primary treatment of invasive carcinoma when tumor size < 5 cm is lumpectomy
+ radiotherapy ± adjuvant therapy ± chemotherapy.
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Sentinel node biopsy is preferred over axillary node dissection.
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Always test for estrogen and progesterone receptors and HER2/neu receptor
protein.
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Primary treatment of inflammatory, tumor size > 5 cm, and metastatic disease
is systemic therapy.
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