When the symptoms of breast cancer do develop, the first sign is usually a lump in the breast tissues. Eighty percent of all women who develop breast cancer will discover a lump on their own. In addition to a palpable lump, any thickening of the skin of the breast or surrounding areas may be a sign of breast cancer.

In the early stages of breast cancer, the lump often moves freely under the skin when manipulated. In the later stages of breast cancer, this lump often adheres to the skin or chest wall, making the lump immovable. A good way to determine the "movability" of a breast lump is to stand before a mirror and raise both arms. If the breast skin puckers or shows any abnormalities from the other breast, these differences may be the symptoms of breast cancer.

In more advanced stages, the symptoms of breast cancer can include swollen bumps or sores on the skin. In some cases, the skin over a lump will look leathery and dimpled. The skin's texture may become "peau d'orange" which means that it takes on the texture of an orange, minus the color. The skin may develop pitting or ridges as a result of breast cancer.

The lymph nodes in the armpit area and under the collar bone may also harden in a patient with breast cancer. These are also usually painless, but may feel a bit tender.

Inflammatory breast cancer, a more rare type of cancer, is characterized by different symptoms of breast cancer. This condition often causes the affected breast to become swollen, red, and warm, as if it were infected. The affected breast often becomes noticeably larger in a short period of time, the nipple may turn inward or produce discharge, and the skin may change its texture as described above. A lump is not typically present in patients who develop inflammatory breast cancer.