Tissue Infiltration in Cancer: Mechanisms, Staging Impact & Treatment Implications

Definition

Invasion of malignant cells beyond the primary tumor into adjacent stroma, organs, or structures.

Key Steps

1. Local invasion – breach basement membrane.
2. ECM degradation – matrix metalloproteinases (MMPs).
3. Migration – amoeboid, mesenchymal, collective.
4. Angio/lymphangiogenesis – vascular highways for dissemination.
5. Intravasation → circulation → extravasation → metastasis.

Clinical Significance

• T category in TNM staging (T1–T4 based on depth/extent).
• Positive margins → higher recurrence risk.
• Guides surgical extent (wide excision vs. organ resection).
• Influences adjuvant therapy decisions.