Cancer: types, causes and treatment
Cancer is uncontrolled cell division that forms a malignant tumour, which can spread (metastasis). It is treated by surgery, radiation, chemotherapy and immunotherapy.
Benign vs malignant tumour
A tumour is a lump of extra cells.
Types of cancer
| Type | Starts in | Example |
|---|---|---|
| Carcinoma | Epithelial tissue (skin and the linings of organs) | Skin, lung, breast, mouth and stomach cancer |
| Sarcoma | Connective tissue: bone, cartilage, muscle, fat | Bone cancer |
| Leukaemia | Blood-forming tissue (bone marrow); too many abnormal white blood cells | Blood cancer |
| Lymphoma | Lymph nodes and lymphatic tissue | Hodgkin's lymphoma |
Causes of cancer (carcinogens)
| Kind | Examples |
|---|---|
| Physical | UV rays from strong sunlight; X-rays and gamma rays |
| Chemical | Tar and other chemicals in tobacco smoke and gutka; benzene; asbestos; arsenic |
| Biological | Some viruses: human papillomavirus (cervical cancer), hepatitis B virus (liver cancer) |
| Other risks | Changes in genes (some run in families), alcohol, an unhealthy diet |
Treatment of cancer
- Surgery: removing the tumour. It works best when the cancer is found early.
- Radiation therapy: high-energy rays, such as gamma rays from cobalt-60, kill cancer cells.
- Chemotherapy: anti-cancer drugs stop cells from dividing. Side effects include hair loss and nausea.
- Immunotherapy: boosting the body's own immune system, for example with interferons.
- Early detection by screening tests and biopsy (testing a small piece of tissue) improves the chance of cure.
Lowering the risk
- Avoid tobacco in every form, and avoid alcohol.
- Eat plenty of fruits and vegetables, and less processed and fried food.
- Protect the skin from strong midday sun.
- Take the HPV and hepatitis B vaccines when advised.
- Go for regular check-ups, and report any unusual lump or sore early.
In India, chewing tobacco and gutka are major causes of mouth cancer. A white or red patch, or a mouth ulcer that does not heal, must be shown to a doctor early.
2 marks: “Distinguish between benign and malignant tumours.” Benign: slow growing, covered by a capsule, does not spread. Malignant: fast growing, invades tissue and spreads by metastasis; this is cancer.
2 marks: “What are carcinogens? Give two examples.” Agents that cause cancer, e.g. tobacco smoke, UV rays, X-rays, human papillomavirus.
7 marks: “What is cancer? Explain its types, causes and treatment.” Define with metastasis; carcinoma, sarcoma, leukaemia, lymphoma; physical, chemical and biological carcinogens; surgery, radiation therapy, chemotherapy, immunotherapy; early detection.
Carcinoma = the covering (epithelium), sarcoma = the support (bone, muscle), leukaemia = the blood (leukos = white), lymphoma = the lymph.