What are signs that a lump could be breast cancer?

Signs+symptoms: The signs and symptoms of breast cancer include: a lump or thickening in or near the breast or in the underarm that persists through the menstrual cycle; change in the size, shape, or contour of the breast; blood-stained or clear fluid discharge from the nipple; change in the feel or appearance of the skin on the breast or nipple (dimpled, puckered, scaly, or inflamed). New lump - see your doc.

Hard to Tell: It is very difficult to distinguish a benign breast lump from a cancer by exam alone, for patient and doctor. In general, cancers tend to be rock-hard, 3-dimensionally round, and can feel "fixed" within the breast. 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) biopsy.

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.