Hello Milky,

This is a bit of difficult question to answer without knowing the context, but let me try.

Yes, there are such things as precancerous lesions.  Generally speaking, a cell is cancerous if it 1)grows and then divides without stopping and 2) can invade other tissues.  Precancerous cells tend to grow and divide without stopping, but they don't invade other tissues.  Precancerous tumors (note that "tumors" are not always cancerous, that is, they don't always invade other tissues) in certain instances become cancerous if untreated.

A common example of this is colon cancer.  In almost all circumstances, colon cancer starts with precancerous lesions, or polyps as they are called in the colon.  These polyps grow bigger.  At some point, they become cancerous, and are then able to invade surrounding tissues.  

Hope this helps.

To your health,

Neil MD