Characterizing the Tumor
When a man has been diagnosed with breast cancer, a number of tests may be performed to determine the stage and type of the disease. This information is vital to choosing the best treatment plan for each individual patient.
There are several types of breast cancer, and sometimes more than one type is seen in the same patient. Tumor characterization is also important in helping determine how likely it is that the cancer will spread to other parts of the body and which type of therapy is most appropriate if it has.
Types of Male Breast Cancer
Any type of breast cancer that occurs in women can also affect men. Some of the more common ones are:
- Infiltrating (or invasive) ductal carcinoma (IDC)
IDC starts in the breast duct and can then break through the duct wall, invading the fatty tissue of the breast. It can also spread to other parts of the body. IDC is the most common type of breast cancer in men.
- Ductal carcinoma in situ (DCIS)
DCIS (also known as intraductal carcinoma) is a pre-invasive cancer, in which cancer cells are contained in the breast ducts, meaning that they do not invade the breast’s fatty tissue or spread outside the breast. It can usually be cured with surgery and radiation therapy.
- Paget disease
This type of breast cancer starts in the breast ducts and spreads to the nipple and, in some cases, to the areola (the dark circle around the nipple). Paget disease may be associated with DCIS or IDC. It is more common in men than in women.
Features of Breast Cancer
The stage of a cancer, sometimes referred to as TNM (tumor, node, metastasis), is used to determine the type of treatment a patient should receive. It is calculated based on several factors:
- The size of the tumor (T)
- Whether or not the cancer has spread to the axillary (armpit) lymph nodes, and if so, to how many (N)
- If the cancer has spread to other lymph nodes of the neck or chest area, or to other parts of the body (M)
Tests that may be used to determine how far a breast cancer has spread include a chest x-ray and blood tests. In some cases, a physician might also order a bone scan, a CT scan, a PET scan, or an MRI scan to assess the extent of the disease.
In about 90 percent of male breast cancer patients, tumors grow in response to the hormones estrogen and/or progesterone. In these tumors, cancer cells have receptors for estrogen (called ER positive), progesterone (PR positive), or both, and are likely to respond to hormonal therapies, which take advantage of the cancer cell’s dependence on hormones for growth. The drug tamoxifen, for example, acts by blocking a tumor’s estrogen receptors.
HER2/neu is a gene that, when activated, helps tumors grow by producing a specific growth-stimulating receptor. Patients with tumors that have more than normal amounts of this protein (called HER2 positive) may benefit from the drug trastuzumab (Herceptin®), which blocks the growth of tumors activated by the gene, or from a similar drug called lapatinib (Tykerb®).
Tumor grade is an evaluation of how abnormal or disorganized the cells from a tumor appear when examined under a microscope. In general, a lower grade implies a less aggressive tumor.
Sometimes tumor cells can invade the blood vessels or the lymph or nerve channels within breast tissue.
Oncotype DX® is a test that is used to analyze the pattern of activity for 21 different genes in patients with a breast tumor that is ER positive but that has not spread to axillary lymph nodes. The pattern is used to predict which patients will benefit most from treatment with chemotherapy in combination with hormonal therapy, and which patients can safely be spared chemotherapy. This test is part of a new and increasingly popular approach called personalized medicine for cancer, in which the molecular features of the specific tumor are analyzed to determine optimal treatment for each individual.