I found small tiny ball under my brest.want to ask is that cancer?

Mondodr's?: Sometimes a vein beneath the breast clots ("mondor's"). Fibroadenomas feel like little balls most of the time. But the bottom line is that a dominant mass in the breast is cancer until proved otherwise. Please get seen.

Signs: A lump is a lump, but a lump that is associated with skin puckering or dimpling, nipple inversion, bloody nipple discharge, or palpable bulky underarm lymph nodes is highly suspicious for cancer. Even in the absence of these things, a lump is no joke--please get this checked out with an examination, mammogram, and possibly a biopsy.

There is no: way to know without getting it evaluated. See your doctor, you might need a mammogram/sonogram.