Breast: Invasive Carcinoma

Invasive Carcinoma

Basics

Risk in United States:
- Women: 12% (1 in 8)
- Men: 0.13%
Time of Progression from a Single-Cell to a 1 cm Tumor: 5-7 Years
Average Survival if Untreated: 2-3 Years
Average Risk of Developing a Second Breast Cancer in the Contralateral Breast: 0.2-0.5% Per Year
Sites of Metastasis:
- Bone – Most Common
- Lung
- Brain
- Liver

Histology of Invasive Carcinoma

Primary Types:
- Invasive Lobular Carcinoma (ILC): Proliferation of Lobule Cells with Basement Membrane Invasion
  - 5-10% of All Invasive Breast Lesions
- Invasive Ductal Carcinoma (IDC): Proliferation of Ductal Cells with Basement Membrane Invasion
  - 70-80% of All Invasive Breast Lesions
Less Common Types:
- Tubular Carcinoma (2-20%) – Well-Differentiated, Favorable Prognosis, Rare Mets & Near 100% Survival
- Mucinous (Colloid) Carcinoma (1-2%) – Well-Differentiated & Favorable Prognosis
- Medullary Carcinoma (1-10%) – Somewhat Favorable Prognosis Despite Poor Differentiation (High-Grade), Associated with BRCA I
- Micropapillary Carcinoma – Particularly Aggressive with Worse Prognosis & High Risk for Nodal Metastases Even if Small
- Tubulolobular Carcinoma
- Metaplastic Carcinoma
- Adenoid Cystic Carcinoma
- Secretory Carcinoma
- Apocrine Carcinoma

Risk Factors

Genetic Mutations

Molecular Receptors

Diagnosis

*See Breast: Breast Mass Evaluation
Location Description:
- Multifocal: Multiple Foci in Same Quadrant
- Multicentric: Involves Multiple Quadrants
  - Increased Risk if Central & Subareolar
Pathology:
- ILC: Small Cells Infiltrate Stroma & Adipose Tissue in a Single-File Pattern
  - Grow in Linear Plane & Infiltrate Between Tissue Planes Rather Than Distorting
  - Cells are Negative for E-Cadherin (Epithelial)
- IDC: Cords & Nests of Tumor Cells with Varying Gland Formation & Fibrotic Response
  - Cells are Positive for E-Cadherin
Difficult to Detect on Frozen Section (Cells Similar to Lymphocytes)

Invasive Lobular Carcinoma ¹

Invasive Ductal Carcinoma ²

TNM Staging

	T	N	M
0	No Evidence of Primary (is – In Situ)	None	None
1	< 2 cm T1mi: ≤ 1 mm T1a: > 1 mm T1b: > 5 mm T1c: > 10 mm	N1mi: Micrometastases (About 200 Cells, 0.2-2.0 mm) N1a: 1-3 Axillary Lymph Node Metastaseswith At Least One ≥ 2.0 mm N1b: Mets in Ipsilateral Internal Mammary Sentinel Nodes N1c: Both N1a & N1b	Distant Mets
2	> 2 cm	N2a: 4-9 Axillary Lymph Node Metastaseswith At Least One ≥ 2.0 mm N2b: Positive Internal Mammary Nodes by Imaging with Pathologically Negative Axillary Nodes
3	> 5 cm	N3a: ≥ 10 Axillary Lymph Node Metastases or Infraclavicular Lymph Node Metastases N3b: N1a or N2a with cN2b (Positive Internal Mammary Nodes by Imaging); or N2a with N1b N3c: Mets in Ipsilateral Supraclavicular Lymph Nodes
4	T4a: Extension into Chest Wall (Not Muscle) T4b: Skin Ulceration or Edema (Peau d’Orange) T4c: Both T4a & T4b T4d: Inflammatory Carcinoma *Invasion of Dermis Alone Does Not Qualify as T4

Treatment

Primary Treatment: Breast-Conserving Therapy (BCT) or Mastectomy
- Margin: Negative Margin (“No Ink on Tumor”)
  - Positive Margin: Re-Excise the Margin
    - If Unsure Which Margin is Positive: Re-Excise All 6 Margins
- Lymph Node Management:
  - Both Options Require Sentinel Lymph Node Biopsy (SLNB)
  - *See Breast: Lymph Node Management
- Breast-Conserving Therapy (BCT) Generally Requires Adjuvant Radiation Therapy
- Contraindications to Breast-Conserving Therapy (BCT):
  - Patient Preference
  - Other Contraindications: *See Breast: Surgical Treatment
Locally Advanced (T3-T4): Consider Neoadjuvant Chemotherapy to Downstage
Stage IV (M1): Palliative Chemotherapy
Adjuvant Therapy:
- Radiation Therapy: *See Breast: Radiation Therapy (RT)
- Chemotherapy: *See Breast: Chemotherapy
- Hormonal Therapy: *See Breast: Hormonal/Endocrine Therapy (HT)

Special Populations

Gestational (Pregnancy-Associated) Breast Cancer
- *See Breast: Special Populations
Male Breast Cancer
- *See Breast: Special Populations