Breast cancer, a malignant breast tumor, led to more than 40,000 deaths and was the cause of almost 210,000 new cancer diagnoses in the U.S. in 2009, according to the National Cancer Institute. Breast cancer development begins in mutant breast cells with genetic mutations which allow the cells to evade cell death and divide out of control. If left untreated, the breast tumor develops into a malignant breast cancer, which can spread throughout the body and prove fatal. Malignant breast tumors have a number of characteristics that allow for advanced cancer development.
Unlimited Cancer Cell Proliferation
One characteristic of a malignant breast tumor is the capacity for unlimited cell proliferation within the tumor. Normal, non-cancerous cells have a limited Hayflick limit--a measure of how many times one cell can divide to give rise to two daughter cells. Malignant cancer cells, in contrast, have gained the ability to proliferate indefinitely, so they can give rise to unlimited numbers of cancer cells. As a result, malignant breast tumors can grow from only a few existing cancer cells. Therefore, during cancer treatment, doctors must work to ensure that the treatment removes or kills all malignant cancer cells, since any remaining cells may give rise to a new tumor and promote breast cancer recurrence.
Ability to Invade Other Tissues
Malignant breast tumors also possess the ability to invade other tissues. This invasive ability helps forms the distinction between benign non-cancerous breast tumors, that cannot invade other tissues and breast cancer. The ability to invade other tissues allows cancer cells to migrate into tissues surrounding the original breast tumor. During breast cancer development, malignant breast tumor cells commonly invade the lymph nodes, small structures that form a part of the immune system. As a result, patients with malignant breast tumors may notice a swelling of the lymph nodes, detectable as a lump under the arm. If left untreated this invasive property of cancer cells allows cells to enter the lymph vessels or the bloodstream and migrate throughout the body.
Ability to Colonize Distant Organs
An important characteristic of malignant breast tumors is the ability of cancer cells within those tumors to colonize distant organs throughout the body. This process is called metastasis, and occurs in the latest stages of breast cancer. The invasive nature of the cells allows them to enter the lymph vessels and bloodstream, but the cells must also be able to colonize distant organs and divide to give rise to tumors within those organs. According to Imaginis, malignant breast tumors most commonly metastasize to bone tissue, as well as the lung or liver. As a result, patients with malignant breast tumors that have metastasized may suffer from bone pain and injury, breathing difficulties or liver damage.
