Breast cancer
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"breast cancer"[MeSH Terms] AND "staging"[MeSH Terms]
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I now have comprehensive material across multiple surgical textbooks. Let me compile the full answer for a medical student.
Breast Cancer: Diagnosis & Staging
1. Clinical Presentation
A breast cancer diagnosis begins with recognizing clinical features. Approximately 30% of patients discover a palpable lump themselves. Other presenting signs include:
- Breast enlargement or asymmetry
- Nipple changes, retraction, or discharge
- Skin changes: erythema, ulceration, or peau d'orange (edema giving an orange-peel texture)
- Axillary mass or lymphadenopathy
- Musculoskeletal discomfort
Breast pain is more commonly associated with benign disease. Up to 50% of women presenting with breast complaints have no physical signs on examination.
Key exam point: Misdiagnosed breast cancer is the leading cause of malpractice claims for diagnostic errors. In women ≤45 years with a palpable mass and equivocal mammography, ultrasound and biopsy are mandatory to avoid diagnostic delay. - Schwartz's Principles of Surgery, 11e
2. Physical Examination
Inspection is performed with arms at sides, then arms raised, then hands on hips (with and without pectoral contraction). Look for:
- Symmetry, size, shape
- Skin retraction, edema (peau d'orange), erythema
Palpation is performed with the patient supine using palmar surfaces of fingers (no grasping/pinching). Examine all quadrants from sternum to latissimus dorsi, clavicle to rectus sheath. Assess all three levels of axillary lymph nodes, plus supraclavicular and parasternal nodes. - Schwartz's Principles of Surgery, 11e
3. Imaging Modalities
Mammography
- Screening mammography: Two standard views in asymptomatic women
- Craniocaudal (CC) view - better for medial breast, more compression
- Mediolateral oblique (MLO) view - images the largest volume including upper outer quadrant and axillary tail of Spence
- Diagnostic mammography: For women with abnormal findings; may add 90° lateral view, spot compression, or other special views
- 3D digital breast tomosynthesis (DBT) improves cancer detection rates and decreases recall rates; used as an alternative screening modality
Ultrasound
- Used in women with a palpable mass
- Axillary ultrasound evaluates nodal involvement in clinically suspicious cases
- Preferred over mammography in women ≤45 years with a mass
MRI
- Not routinely recommended for all newly diagnosed breast cancer
- Indicated when disease extent is difficult to define by mammography + ultrasound
- Annual breast MRI + mammography for high-risk women (≥20% lifetime risk, prior chest RT aged 10-30 years) - Current Surgical Therapy, 14e
PET/CT
- Not indicated for clinical Stage I or II or operable Stage IIIA (T3N1) disease
- Reserved for high-risk (clinical Stage III) patients to evaluate for distant metastases
- Also used when signs/symptoms suggest distant disease (bone pain, elevated ALP, abdominal symptoms, pulmonary complaints)
4. Biopsy and Pathologic Diagnosis
Core needle biopsy (CNB) is the standard method for tissue diagnosis in suspicious lesions.
Biopsy provides:
- In situ vs. invasive disease
- Histologic variant (ductal, lobular, mixed)
- Hormone receptor status: ER, PR, HER2
- Tumor grade
BI-RADS Classification (ACR Breast Imaging Reporting and Data System)
| Category | Description | Action |
|---|---|---|
| 1 | Negative | Routine screening |
| 2 | Benign finding | Routine screening |
| 3 | Probably benign | Short-term follow-up (6 months) |
| 4 | Suspicious | Biopsy recommended |
| 5 | Highly suggestive of malignancy | Biopsy required |
| 6 | Known biopsy-proven malignancy | Management planning |
Indications for stereotactic core biopsy include BI-RADS 3-6, new suspicious microcalcifications, developing asymmetries, architectural distortions, and nonpalpable densities not seen on ultrasound. - Current Surgical Therapy, 14e
5. Histologic Subtypes
Most invasive breast cancers are carcinomas arising from epithelial elements. Frequency (SEER database, n=135,157):
| Subtype | Frequency |
|---|---|
| Infiltrating ductal carcinoma (IDC) | 76% |
| Invasive lobular carcinoma | 8% |
| Ductal/lobular mixed | 7% |
| Mucinous/colloid | 2.4% |
| Tubular | 1.5% |
| Medullary | 1.2% |
| Papillary | 1% |
IDC is the most common type - firm, gray-white, gritty mass on gross pathology; characterized by cords/nests of tumor cells with variable gland formation and desmoplastic stromal reaction (stellate shape). Often associated with DCIS. - Mulholland & Greenfield's Surgery, 7e
6. AJCC TNM Staging (8th Edition)
The 8th edition AJCC system is internationally accepted for characterizing disease extent, predicting prognosis, and guiding management. It expanded beyond anatomy to include prognostic staging incorporating tumor grade, ER/PR/HER2 receptor status, and genomic scores.
T - Primary Tumor
| T | Definition |
|---|---|
| Tis | Carcinoma in situ (DCIS) or Paget's disease of nipple with no tumor; LCIS is now considered benign |
| T0 | No evidence of primary tumor |
| T1 | Invasive cancer ≤20 mm (T1a ≤5 mm; T1b >5-10 mm; T1c >10-20 mm) |
| T2 | >20 mm but ≤50 mm |
| T3 | >50 mm |
| T4 | Any size + direct extension to chest wall OR skin (edema, ulceration, satellite nodules) |
| T4d | Inflammatory breast cancer (IBC) - skin changes involving ≥1/3 of breast skin |
Note: Invasion of dermis alone does NOT qualify as T4.
N - Regional Lymph Nodes
Regional nodes = ipsilateral axilla, ipsilateral intramammary, internal mammary, and supraclavicular nodes. Metastasis to contralateral axilla or cervical nodes = M1 (distant disease).
Clinical (cN):
| cN | Criteria |
|---|---|
| cN0 | No regional LN metastases |
| cN1 | Mobile ipsilateral level I/II axillary nodes |
| cN2 | Fixed/matted axillary nodes OR clinically detected internal mammary nodes without axillary involvement |
| cN3 | Infraclavicular, ipsilateral internal mammary + axillary, or supraclavicular nodes |
Pathologic (pN):
| pN | Criteria |
|---|---|
| pN0 | No regional LN metastases (must be >0.2 mm and >200 cells to count) |
| pN1mi | Micrometastases: >0.2 mm but none >2.0 mm |
| pN1 | Metastases in 1-3 axillary nodes ±internal mammary by SLN biopsy |
| pN2 | Metastases in 4-9 axillary nodes OR clinically detected internal mammary nodes |
| pN3 | ≥10 axillary nodes, infraclavicular (Level III), supraclavicular, or combinations |
M - Distant Metastases
| M | Definition |
|---|---|
| M0 | No distant metastasis |
| cM0(i+) | No clinical/radiographic evidence but microscopically detected tumor cells (≤0.2 mm) in blood, marrow, or non-regional nodes |
| M1 | Detectable distant metastases >0.2 mm |
Stage Groupings
| Stage | T | N | M |
|---|---|---|---|
| 0 | Tis | N0 | M0 |
| I | T1 | N0 | M0 |
| IIA | T0-T1 | N1 | M0 or T2 N0 M0 |
| IIB | T2 | N1 | M0 or T3 N0 M0 |
| IIIA | T0-T3 | N2 | M0 or T3 N1 M0 |
| IIIB | T4 | N0-N2 | M0 |
| IIIC | Any T | N3 | M0 |
| IV | Any T | Any N | M1 |
- Mulholland & Greenfield's Surgery, 7e; Current Surgical Therapy, 14e; Schwartz's Principles of Surgery, 11e
7. Workup Summary for a Newly Diagnosed Patient
- History & physical exam - palpable mass characterization, axillary examination
- Bilateral mammography ± ultrasound - define disease extent
- Core needle biopsy - histology, grade, ER/PR/HER2
- Axillary ultrasound - if clinically suspicious nodes
- Assign clinical stage (cTNM) based on tumor size + nodal status
- Further imaging (CT chest/abdomen/pelvis ± bone scan ± PET):
- Reserved for clinical Stage III or signs/symptoms of distant disease
- NOT indicated for Stage I-II or operable Stage IIIA (T3N1)
- Pathologic staging (pTNM) after surgical resection
- Receptor status + grade → guide adjuvant therapy decisions
High-Yield Exam Points
- Most common subtype: Infiltrating ductal carcinoma (IDC) - 76%
- IBC (T4d): Skin involvement ≥1/3 of breast; classified as Stage IIIB at minimum
- LCIS: No longer a "Tis" in AJCC 8th edition - considered benign, managed with surveillance
- pN1mi vs pN1: Micrometastases (>0.2 mm but ≤2 mm) are pN1mi; macrometastases in 1-3 nodes = pN1
- cM0(i+): Circulating tumor cells with no clinical/radiographic metastases - still classified as Stage I-III
- AJCC 8th edition added prognostic (biologic) staging incorporating ER/PR/HER2/grade - a major change from 7th edition
- BI-RADS 3 = short-term 6-month follow-up; biopsy NOT automatically required unless clinical suspicion is high
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