& Tumor Revision Sheet

1. 📌 Essentials

• Tumor: abnormal cell proliferation within tissue; benign or malignant.
• Benign tumors: localized, well-differentiated, regular contour.
• Malignant tumors: invasive, poorly differentiated, irregular contour, capable of metastasis.
• Carcinogenesis: multistep process involving initiation, promotion, progression.
• Key genes: proto-oncogenes (promote mitosis), anti-oncogenes (suppress mitosis).
• Mutations: activate proto-oncogenes into oncogenes; inactivate anti-oncogenes.
• Tumor progression: hyperplasia → dysplasia → in situ → invasive → metastasis.
• Major risk factors: environmental (smoking, chemicals, viruses, UV) and endogenous (genetics, hormones).
• Detection tools: imaging (X-ray, CT, MRI, scintigraphy), histopathology, tumor markers.
• Treatments: surgery, chemotherapy, radiotherapy, immunotherapy, targeted therapy.

2. 🧩 Key Structures & Components

• Tumor mass — abnormal cell growth forming a lump.
• Oncogenes — mutated proto-oncogenes driving excessive mitosis.
• Anti-oncogenes (Tumor suppressor genes) — inhibit cell cycle progression.
• Vasculature — increased in malignant tumors (angiogenesis).
• Metastatic pathways — lymphatic and hematogenous spread.
• Tumor markers — substances like PSA, CEA, AFP detectable in blood.
• Mutagens — viruses (HPV, EBV), chemicals, UV radiation.
• Stromal tissue — supports tumor growth; includes fibroblasts, immune cells.
• Histopathological features — cellular differentiation, mitotic rate, nuclear atypia.
• Imaging modalities — X-ray, CT, MRI, scintigraphy.

3. 🔬 Functions, Mechanisms & Relationships

• Mutation of proto-oncogenes → oncogene activation → increased cell proliferation.
• Inactivation of anti-oncogenes (e.g., p53, RB) → loss of growth control.
• Progression involves genetic instability, leading to dysplasia, invasion, metastasis.
• Angiogenesis supplies nutrients, enabling tumor growth and dissemination.
• Tumor invasion breaches basement membrane, infiltrates adjacent tissues.
• Metastasis occurs via lymphatic or hematogenous routes, establishing secondary tumors.
• Detection: imaging reveals tumor size/location; histopathology confirms malignancy.
• Treatment: surgery removes localized tumors; chemo/radiotherapy target proliferating cells.

4. Comparative Table: Benign vs Malignant Tumors

5. 🗂️ Hierarchical Diagram (ASCII)

Tumor & Cancer
 ├─ Benign Tumors
 │    ├─ Lipoma
 │    ├─ Fibroma
 │    └─ Nevus
 └─ Malignant Tumors
      ├─ Carcinomas (epithelial origin)
      │    ├─ Squamous cell carcinoma
      │    └─ Adenocarcinoma
      └─ Sarcomas (mesenchymal origin)
           ├─ Osteosarcoma
           └─ Liposarcoma

6. ⚠️ High-Yield Pitfalls & Confusions

• Confusing benign with malignant based solely on size.
• Mistaking dysplasia for invasive carcinoma; dysplasia is pre-invasive.
• Overlooking metastasis in early-stage tumors.
• Assuming all tumors with irregular contour are malignant.
• Misidentifying tumor markers; not all are specific.
• Believing all carcinogens cause direct mutations; some promote via inflammation.
• Confusing proto-oncogenes (normal) with oncogenes (mutated).
• Underestimating the role of angiogenesis in tumor growth.
• Ignoring the importance of genetic mutations in carcinogenesis.

7. ✅ Final Exam Checklist

• Define tumor, benign, malignant.
• Describe the stages of carcinogenesis.
• List key genes involved: proto-oncogenes, anti-oncogenes.
• Explain the process of tumor progression.
• Identify major risk factors: environmental and endogenous.
• Recognize common tumor types and their features.
• Differentiate between benign and malignant tumors macroscopically and microscopically.
• Understand the role of angiogenesis in tumor growth.
• Know diagnostic tools: imaging, histopathology, tumor markers.
• List main treatment options and their mechanisms.
• Recognize common pitfalls in tumor diagnosis.
• Explain the significance of metastasis pathways.
• Recall major tumor markers and their clinical relevance.
• Understand the genetic basis of tumor development.
• Be familiar with the concept of tumor staging and grading.
• Know preventive measures: reducing mutagen exposure, vaccination, screening.

---