Breast cancer typically starts as a small group of cells in the breast that begin to grow in an out-of-control manner. Consequently, some of the earliest effects of breast cancer are localized lumps and masses within the breast. Because these tumors are the result of abnormal cell growth, they will feel "different" from the surrounding tissue. These lumps may feel firmer than the surrounding tissue, or may be painful or immobile. Also, because the tumors grow without the normal support of the connective tissue, they can cause changes to the breast's surface. This can cause changes in the nipple or dimpling of the skin. Because the tumors can also disrupt the ducts leading to the nipple, breast cancer can cause discharge to come from the nipple.
Effects of Metastasis
One of the hazards of breast cancer is its ability to spread to other tissues (a process known as metastasis). According to the Mayo Clinic, breast cancer can most easily spread to the bones, the liver and the lungs. Consequently, breast cancer can cause dysfunction of these organs. Metastasis to the bones can cause bone pain and easy fracturing. If the cancer spreads to the lungs it can cause trouble breathing, a chronic cough and pneumonia. Finally, metastasis to the liver can cause abdominal pain, jaundice and problems with the clotting of blood.
There are some symptoms of breast cancer that are common for most types of cancer. These tend to be the effects that cancer has on the body as a whole. For example, people with breast cancer often suffer from extreme fatigue and a lack of energy. They may also suffer from nausea, a lack of appetite, and may have sudden and unexplained weight loss.