The most common sign of breast cancer is a new lump or mass. A mass that is painless, hard, and has irregular edges is more likely to be cancerous, but some rare cancers are tender, soft, and rounded.
Other Symptoms
A generalized swelling of part of a breast (even if no distinct lump is felt).
Breast skin irritation or dimpling.
Nipple pain or retraction (turning inward), redness or scaliness of the nipple or breast skin.
Discharge other than breast milk.
Many of these symptoms can also be due to benign breast conditions but medical examinations and tests may be the only way to determine their cause.