How can you tell if a breast lump is cancerous?

Breast Biopsy: It is very difficult to distinguish a benign breast lump from a cancer for patient and doctor. Depending upon age and physical examination findings, we will often get a mammogram and ultrasound to help evaluate a breast lump, sometimes culminating in a (nonsurgical) needle-biopsy--ultimately, the only way to be 100% certain is to look at the tissue under the microscope.

Imaging/Biopsy: Through imaging and a biopsy.