Cancer is a genetic disease caused by changes (mutations) to the DNA that control how cells divide, function, and die.
Source: National Cancer Institute (.gov)
1. Details & Development (How it Happens)
- Fundamental Cause: Stems from DNA mutations due to genetic inheritance, cell division errors, or environmental exposures (tobacco, radiation, viruses).
- Abnormal Division: Cancer cells ignore signals for apoptosis (programmed cell death), forming masses called tumors.
- Metastasis: Malignant cells can break away and travel through the bloodstream or lymphatic system to other organs.
- Tumor vs. Non-Tumor: While most form solid tumors, blood cancers like leukemia crowd out normal cells in the bone marrow instead.
2. Properties of Cancer Cells
Known as the "hallmarks of cancer," these cells differ from normal cells in several ways:
- Uncontrolled Proliferation: Dividing without growth signals.
- Immortalization: Evading programmed death to live indefinitely.
- Angiogenesis: Growing their own blood vessels for nutrient supply.
- Immune Evasion: Tricking the immune system to avoid destruction.
- Genomic Instability: Accumulating high levels of mutations to adapt.
3. Function & Impact on the Body
Cancer cells consume resources intended for healthy cells, disrupting vital functions.
- Tissue Destruction: Invading surrounding tissues and destroying organ function.
- Metabolic Changes: Altering energy usage, often leading to cachexia (extreme weight loss).
- Systemic Symptoms: Fatigue, unexplained pain, fever, and weight loss.
Source: Mayo Clinic
4. Kinds of Cancer (Classifications)
- Carcinoma
- The most common type, starting in skin or internal organ linings (e.g., breast, lung, colon).
- Sarcoma
- Begins in connective tissues like bone, fat, muscle, or blood vessels.
- Leukemia
- Cancer of the white blood cells starting in the bone marrow.
- Lymphoma & Myeloma
- Cancers specifically affecting the immune system (lymphocytes).
- CNS Tumors
- Cancers arising in the brain and spinal cord.
Source: Cancer Research UK