Please explain what are the chances of a lump in the breast being cancer?

Depends: The vast majority (98%) of breast lumps are benign. If a lump needs to be biopsied, there is about a 20% chance it's cancer. These are estimates, and there are certain characteristics that make a lump more or less likely to be cancer. A rock-hard lump is more suspicious, as is one that has been growing over time.

Depends: This depends on how the lump feels compared to the normal lumpiness of your breast. There are many non cancerous lumps that are very common. I recommend you see your doctor for a breast evaluation and get a mammogram.