Some specialists begin this staging with Stage 0, which is not normally cancer at all, but only a non-invasive breast cancer, in fact an abnormal cell formation that will turn into cancer only if it is nor removed.

Breast cancer stages normally begin with Stage I, where we already have cancer cells that started to multiply and migrate to the neighbouring tissue. It's an incipient tumour that can have a dimension of up to 2 centimetres. If the patient is lucky enough to have a mammogram or some special screening , the doctor will be able to identify it and recommend surgery.I have to mention that the tumour is only in one place and has not started to migrate to the lymph nodes yet, but you can find it only in the breast.
Stage II can take a longer time, so some oncologists divide it into two separate parts : stage II A and B. The A one descibes different scenario where the tumour may have between 2 and 5 cm but it is not extended to the nodes or there's no tumour identified but the armpit lymph nodes are swollen and hurt or both (there is a small tumour that has spread to the nearby lymph nodes - in this case the tumour is less than 2 cm). Stage IIB is a kind of combination - the tumout is small and spread or is big (larger than 5 cm) and did not spread.

Stage III is the stage in which most breast cancers are detected because now the cancer leaves its initial location and starts spreading around. This causes some tissue disruptures and they hurt. The tumour also grows in size and it is now palpable. Normally this stage, too, is divided into a lot of substages, but I will leave them only to the specialists. First the cancer spreads to the lymph nodes and then, little by little, invades the other organs in the body. Here, in stage III it only gets to the lymph nodes and sometimes to the chest bone and muscle.
Stage IV is called metastatic cancer because there are now metastases to different parts of the body, sometimes really distant from the initial starting point. Breast cancer usually has mets to the liver, lungs, intestines or even bones.