Cancer

Cancer is a disease in which some body cells start dividing in an uncontrolled way and can form a lump called a tumour (or spread to other parts of the body).

• Why it happens: Cells normally follow “rules” for when to grow, divide, and stop. In cancer, these rules get disturbed because of changes in the cell’s control system (often linked to damage in genetic material).
• Not contagious: Cancer is a non-communicable disease, so it does not spread from one person to another by touch, air, water, or food.
• Benign vs malignant tumours: Some tumours are benign (stay in one place and usually are less dangerous). Malignant tumours can invade nearby tissues and may spread through blood or lymph to other organs; this spreading is called metastasis.
• Risk factors: Things like tobacco (smoking or chewing), unhealthy diet, certain chemicals, radiation (like UV rays), and air pollution can increase risk by damaging cells over time.
• Infections can be involved (but cancer still isn’t “catching”): A few cancers are linked to certain viruses or infections (for example, HPV is linked to cervical cancer). The infection may raise risk, but cancer itself is not passed person-to-person like flu.
• Why screening matters: Cancer often becomes easier to treat when found early, so tests like check-ups and screening help detect changes before they become severe.

Think of it like a factory where machines (cells) are supposed to stop when enough products are made—cancer is when a few machines lose the “stop” switch and keep producing more and more.