What Is Cancer?
Cancer is one of the most feared words in the world. Cancer is not just one disease — it’s a group of over 100 different diseases that all involve uncontrolled growth of abnormal cells in the body.
Normally, your body’s cells grow, divide, and die in a very organized way. Old or damaged cells are removed, and new ones take their place.
But in cancer, this process breaks down. Cells:
- Start growing out of control
- Don’t die when they should
- May invade nearby tissues
- Can even spread (metastasize) to other parts of the body
This uncontrolled growth forms tumors (except in cancers like leukemia, which affect blood and bone marrow).
What Causes Cancer?
Cancer is caused by changes (called mutations) in the DNA inside your cells. DNA is like your cell’s instruction manual — and when it gets damaged, the cell may start acting abnormally.
These mutations can be:
- Inherited (from your parents)
- Acquired during life (due to environment, lifestyle, or random error)
Common Risk Factors:
| Risk Factor | How it contributes |
| Smoking | Linked to lung, mouth, throat, and many other cancers |
| Obesity | Creates chronic inflammation and hormonal imbalances |
| Poor Diet | Lack of fiber, antioxidants; excess sugar or processed meat |
| Alcohol | Increases risk for liver, breast, and esophageal cancer |
| Radiation | UV rays (skin cancer), X-rays, and environmental exposure |
| Infections | HPV (cervical cancer), Hepatitis B/C (liver cancer), H. pylori (stomach) |
These factors don’t guarantee cancer will develop — but they significantly increase risk.
How Does Cancer Grow?
Cancer begins with one damaged cell that ignores the body’s normal rules. Here’s a simplified step-by-step:
- DNA Mutation happens in a single cell.
- That cell begins to divide uncontrollably.
- A tumor forms as the abnormal cells pile up.
- The tumor may grow its own blood vessels to feed itself (angiogenesis).
- It can invade nearby tissues and eventually spread through blood or lymph.