Unit 7.4 — Cancer Notes 🔬
1. Why cancer matters 😷
Cancer is among the leading causes of death worldwide. Over a million people in India alone face it each year, and many lives are lost. Understanding how normal body cells slip out of control helps us fight the disease more effectively.:contentReference[oaicite:0]{index=0}
2. How healthy cells keep order 🧩
- Normal cells grow, divide, and mature only when needed.
- They stop dividing once they touch their neighbors — a safety check called contact inhibition.:contentReference[oaicite:1]{index=1}
3. What goes wrong in cancer 🚨
- Loss of contact inhibition lets cells multiply nonstop.
- The result is a tumor — a lump of extra cells.:contentReference[oaicite:2]{index=2}
3.1 Two kinds of tumors
| Type | Main features |
|---|---|
| Benign 😊 | Stays at its starting point, grows slowly, usually causes little harm.:contentReference[oaicite:3]{index=3} |
| Malignant ⚠️ | Grows fast, invades nearby tissues, steals nutrients, and sends rogue cells through the blood to seed new tumors elsewhere — a spread called metastasis.:contentReference[oaicite:4]{index=4} |
4. What triggers cancer? 🔍
- Physical agents: X-rays, γ-rays (ionising) and UV light (non-ionising) can damage DNA.:contentReference[oaicite:5]{index=5}
- Chemical agents: e.g., tobacco-smoke chemicals linked to lung cancer.:contentReference[oaicite:6]{index=6}
- Biological agents: oncogenic viruses carry viral oncogenes.
- Proto-oncogenes (c-onc) in our own DNA can flip into cancer-drivers if inappropriately activated.:contentReference[oaicite:7]{index=7}
5. Spotting cancer early 🔦
- Biopsy + histopathology: A tiny tissue slice is stained and checked under a microscope for abnormal cells.:contentReference[oaicite:8]{index=8}
- Blood / bone-marrow counts: Helpful in leukemias.
- Imaging: Radiography (X-ray), CT scans (3-D X-ray images), and MRI (magnetic fields + radio waves) reveal hidden tumors.:contentReference[oaicite:9]{index=9}
- Antibody tests: Detect cancer-specific molecules.
- Molecular genetics: Hunting for inherited “cancer-susceptibility” genes so that high-risk individuals can avoid triggers (e.g., tobacco smoke).:contentReference[oaicite:10]{index=10}
6. Treating cancer 🛠️
- Surgery: Remove the tumor mass.
- Radiotherapy: Zap tumor cells with lethal radiation while sparing nearby healthy cells.:contentReference[oaicite:11]{index=11}
- Chemotherapy: Drugs that kill or stop cancer cells. Some target specific tumors; side effects include hair loss and anemia.
- Immunotherapy: Boost the body’s defenses using substances such as α-interferon (a biological response modifier).:contentReference[oaicite:12]{index=12}
- Most cases use a combo of surgery, radiation, and chemo for the best shot at a cure.
7. Important Concepts for NEET ✨
- Loss of contact inhibition and unchecked cell division.
- Benign vs. malignant tumors — especially the idea of metastasis.
- Roles of carcinogens: physical (radiations), chemical (tobacco smoke), and biological (oncogenic viruses, proto-oncogenes).
- Key detection methods: biopsy, histopathology, CT, MRI, antibody tests.
- Main treatments: surgery, radiotherapy, chemotherapy, immunotherapy with α-interferon.
🌟 Stay curious, stay proactive, and remember: early detection saves lives! 🌟
