How to tell if it's breast cancer in a lump?

Eval by breast surg: If there's a new lump that's drawing attention/concern, seek immediate medical attention and referral to a breast surgeon. Beyond clinical impression, imaging will often suggest what the lesion is but the most definitive diagnosis usually comes via a needle (i.E aspiration or core biopsy).

Biopsy: The only way to know for sure if a breast lump is cancer or not is with a biopsy - a procedure in which a small amount of the lump is removed and then examined by a pathologist under the microscope. Mammogram, ultrasound and MRI can give a good idea if a lump is cancer or not, and depending on the results of imaging studies, biopsy may not be necessary.

Pathologist: The lump should be biopsied or removed and the tissue examined by a pathologist to arrive at the correct diagnosis.