Ijpsr (2009), Issue 1, Vol

How Cancer Grows: A cancer can continue to grow because cancer cells act differently than normal cells. Cancer cells have the same needs as normal cells. Cancer cells need nutrients and oxygen from blood vessels to survive and grow. The tumor can easily grow by nutrients and oxygen. They need a blood supply to bring oxygen and nutrients to grow and survive. When a tumor is very small, it can easily grow, and it gets oxygen and nutrients from nearby blood vessels. Cancer cells are different from normal cells because of they:

• 
  Divide out of control
  
• 
  They are immature and don’t develop into mature cells with specific jobs.
  
• 
  Avoid the immune system.
  
• 
  Ignore signals that tell them to stop dividing or to die when they should.
  
• 
  Don’t stick together very well, and through blood or lymphatic system, they can spread to other body parts.
  
• 
  Grow into and damage tissues and organs.
  

FIG. 2: HOW CANCER GROWS
How it Spread: As the tumor grows, the cancer cells are carried with the lymphatic system or bloodstream to other body parts, Then the cancer cells may be developed into new tumors and it is called metastasis. Cancer may spread to lymph nodes, which are bean-shaped organs and tiny that helps to fight with infection. Neck; underarms and groin area etc. these are the body parts where the lymph nodes are located. Cancer may also spread through the bloodstream to other body parts like the liver, bones, brain, or lungs. If cancer spreads to different body parts from that area where it began than it is named as metastatic cancer of that particular area where it starts.
For example, if lung cancer spreads to the breast than it is called metastatic lung cancer, not breast cancer.
Common Cancers: There are more than 100 cancers which affect humans but commonest among all are: Bladder, breast (female-malele), endometrial, thyroid, colorectal cancer, leukemia, lung (including bronchus), melanoma, kidney (renal cell and renal pelvis) cancer, non-Hodgkin lymphoma, prostate, pancreatic cancer ^17-19.