Local spread of the tumor occurs deep into the chest wall and its associated structures (ribs, pleura and brachial plexus), or outwards, on the skin. In the lymphatic system, the tumor spreads to the axillary and supraclavicular lymph nodes, as well as to the intraorgan lymph network or the contralateral. Metastases of hematogenous origin mainly occur in the bones (especially in the axial skeleton), liver, lungs, skin and in the organs of the central nervous system (brain and spinal cord). Often they are found in the area of the peritoneum and pelvis, including the ovaries and adrenal glands.
An unusual spread of a tumor is often noted, for example, extensive metastasis of bones without signs of soft tissue damage. Some patients have an aggressive local tumor recurrence, the so-called en cuirasse cancer (scleroderm-like form), which is not accompanied by the formation of distant metastases. A tumor in the form of an extensive ulcer affects a large part of the chest wall. The reasons for such aggressiveness of the tumor are unclear, but it is not associated with its histological characteristics and with the stage of development.
Hematogenous tumor proliferation plays a critical role because patients die from distant metastases, and not from its local growth. The probability of metastasis to the axillary lymph nodes is well correlated with the size of the primary tumor. Identified the relationship between the number of affected lymph nodes and survival. Affection of the internal lymph nodes is an early and important sign of the existence of a tumor located in the central zone of the mammary gland.