Diagnosis of breast cancer usually involves several steps, including examination of the breast, mammography, ultrasound testing, and biopsy. Biopsy is the only definitive way to diagnose breast cancer.

• Mammograms are X-rays of the breast that may help define the nature of a lump. Mammograms are also recommended for screening to find breast cancer. Usually, it is possible to tell from the mammogram whether a lump in the breast is cancerous, but no test is 100% reliable. Mammograms are thought to miss as many as 10-15% of breast cancers.

• Ultrasound of the breast is often done to evaluate a breast lump. Ultrasound waves create a ‘picture’ of the inside of the breast. It can demonstrate whether a mass is filled with fluid (cystic) or if it is solid. Cysts can be benign, but solid lumps are generally cancerous. Ultrasound may also be used to guide a biopsy or removal of fluid.

• Biopsy is the best way to diagnose breast cancer. It includes removing a tiny piece of tissue from the affected part of the breast for examination and testing by a pathologist to determine if cancer is present. Varied biopsy techniques are available.