About This Page
This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.
Key points
- USPSTF recommends biennial screening mammography for women aged 40-74 years
- Diagnostic workup of a suspicious mass: diagnostic mammography plus targeted ultrasound, followed by core needle biopsy
- Receptor status drives treatment: ER/PR-positive, HER2-positive, or triple-negative
- Breast-conserving surgery plus radiation has survival similar to mastectomy for eligible early-stage disease
- Inflammatory breast cancer presents with erythema, edema, peau d’orange, and requires urgent biopsy and neoadjuvant therapy
Overview
Breast cancer is a heterogeneous group of malignancies, most often invasive ductal carcinoma or invasive lobular carcinoma. Evaluation integrates imaging, pathology, receptor status, grade, stage, and genetics. Treatment combines local therapy with surgery/radiation and systemic therapy with endocrine treatment, chemotherapy, HER2-targeted therapy, immunotherapy, or targeted agents depending on subtype.
Epidemiology
Breast cancer is the most common non-skin cancer in women in the United States and a leading cause of cancer death. Risk factors include age, female sex, family history, BRCA1/2 or other pathogenic variants, prior chest radiation, atypical hyperplasia or LCIS, dense breasts, early menarche, late menopause, nulliparity or late first pregnancy, postmenopausal hormone therapy, alcohol use, and obesity after menopause.
Clinical Features
Symptoms
Painless breast mass or thickening
Nipple discharge, especially spontaneous unilateral bloody discharge
Nipple inversion, skin dimpling, or eczematous nipple changes suggesting Paget disease
Breast erythema, warmth, edema, peau d’orange suggesting inflammatory breast cancer
Bone pain, dyspnea, weight loss, or neurologic symptoms suggesting metastases
Signs
Hard irregular fixed mass
Axillary or supraclavicular lymphadenopathy
Skin tethering, dimpling, ulceration, peau d’orange
Paget disease: scaly erythematous nipple lesion
Investigations
First-line
Screening mammographyRoutine screening detects asymptomatic disease; USPSTF biennial ages 40-74
Diagnostic mammography and targeted ultrasoundUsed for palpable mass or abnormal screening result; ultrasound helps characterize cystic versus solid lesions
Core needle biopsyPreferred tissue diagnosis for suspicious lesion; provides histology and receptor testing
Second-line
ER, PR, HER2 testingRequired on invasive breast cancer to guide endocrine and HER2-targeted therapy
Breast MRIUsed for selected high-risk screening, extent of disease, occult primary, or problem-solving
Genetic counseling/testingIndicated for young age at diagnosis, triple-negative disease at young age, strong family history, male breast cancer, or ovarian/pancreatic/prostate cancer patterns
Specialist
Staging imagingNot routine for asymptomatic early-stage disease; use when locally advanced disease or symptoms suggest metastases
Sentinel lymph node biopsyAxillary staging in clinically node-negative invasive cancer
1
Screening and diagnosis
- Biennial mammography ages 40-74 per USPSTF; higher-risk patients may need earlier MRI-based screening
- Triple assessment: clinical examination, imaging, and tissue diagnosis
- Do not reassure a persistent palpable mass solely because screening mammogram was normal; pursue diagnostic imaging and biopsy as indicated
2
Early-stage local therapy
- Lumpectomy plus radiation or mastectomy depending on tumor size, location, patient preference, genetics, and contraindications
- Sentinel lymph node biopsy for nodal staging when clinically appropriate
- Radiation after breast-conserving surgery; post-mastectomy radiation for selected higher-risk disease
3
Systemic therapy by subtype
- ER/PR-positive: endocrine therapy such as tamoxifen or aromatase inhibitor depending on menopausal status and risk
- HER2-positive: trastuzumab-based therapy with cardiac monitoring
- Triple-negative: chemotherapy; immunotherapy may be used in selected high-risk or metastatic settings
- Neoadjuvant therapy for inflammatory, locally advanced, HER2-positive, or triple-negative tumors when appropriate
Complications
- Metastases: Bone, liver, lung, brain
- Lymphedema: After axillary surgery/radiation
- Cardiotoxicity: Anthracyclines and HER2-targeted therapy require monitoring
- Endocrine therapy effects: Tamoxifen increases VTE/endometrial cancer risk; aromatase inhibitors reduce bone density
USMLE Step 2 CK Exam Tips
- 1Palpable breast mass: diagnostic mammogram and ultrasound, then core needle biopsy if suspicious
- 2Bloody unilateral nipple discharge is concerning and needs evaluation
- 3Inflammatory breast cancer: erythema + peau d’orange + no improvement with antibiotics = biopsy
- 4ER-positive disease gets endocrine therapy; HER2-positive disease gets trastuzumab-based therapy
- 5Triple-negative breast cancer is associated with BRCA1 and is more aggressive
- 6Lumpectomy plus radiation has survival similar to mastectomy in eligible early breast cancer
- 7Tamoxifen risk: endometrial cancer and VTE; aromatase inhibitor risk: osteoporosis
Put your reading into practice
Topic-specific question practice is not linked for this article yet.
Choose USMLE Step 2 CK questions from the existing bank. General exam practice covers your selected topics; it is not filtered to this article. Your usual question-bank access applies.
Choose USMLE Step 2 CK practiceAfter your session, return to this section to revisit the reading and choose your next review.
Verified Sources & References
related resources
Save your place and choose what comes next
Hematology & Oncology · Article 22 of 24