Is a lump on breast cancerous? Learn about the warning signs of breast cancer, including changes in the breast and nipple. Sometimes it can develop without warning, but many cases have warning signs. breast cancer; colon cancer that has spread (metastasized) can cause pain. For. Jul 01, · The most common sign of breast cancer is a new breast lump or mass. Breast Cancer Signs and Symptoms. Breast or nipple pain;.