By Margot Heffernan, MLS
The architecture of breast tissue is not homogenous, as it is made up of lobules, ducts, fat and connective tissue. These distinct tissue types define the histology, or structure of the breasts. Breast cancer usually originates in either the ducts or lobes. Breast cancer histology helps to determine treatment choices for breast cancer and is also a factor in how clearly breast cancer is visualized on a mammogram.
The majority of invasive breast cancers originate in the ducts, the complex network of channels that transport milk from the lobules to the nipple. This type, called ductal breast cancer, is considered “invasive” when cancer cells break through the duct and “invade” the adjacent healthy breast tissue. A diagnosis of invasive ductal breast cancer, or IDC, does not describe the extent of the spread of breast cancer in the body; it simply means that the cancer cells are no longer contained within the walls of the duct. Hence, IDC can be confined to different parts of the breast structure itself, or it can be present in the lymph nodes under the arm, or other organs of the body. If IDC spreads to other regions or organs of the body, it is called metastatic breast cancer. Invasive, or infiltrating ductal breast cancer accounts for up to 85% of all breast cancer diagnoses.
Lobular breast carcinoma (LBC), which constitutes 10-15% of all breast cancers, is the second most common type of breast cancer. LBC begins in the lobules of the breast, the glands that produce milk in a lactating woman. Like IDC, lobular breast cancer can break out of the structure from which it originated – in this case the lobules – and travel to the adjacent breast tissue, the lymph nodes under the arms, or to distant organs. When this happens, it is called invasive or infiltrating lobular breast cancer. As is the case with all cancers, when LBC invades other organs it is defined as metastatic disease.
Although mammography is considered the gold standard of breast cancer diagnosis, invasive lobular breast cancer presents a special diagnostic challenge for radiologists because it does not always image in a predictable or clear way. Unlike the histology of ductal breast carcinoma, the minute structure of ILC is characterized by small, relatively uniform cells that line up in a linear fashion. The progression of lobular cancer from the lobes to the surrounding breast tissue ultimately forms a more diffuse and web like pattern within the breast; it is less likely than ductal breast cancer to form a discrete lump that can be visualized on a mammogram or felt by a clinical breast examination.
Because mammography is limited in its ability to diagnose ILC, the reported false negative rate of this imaging study ranges from 8% to 19%. This probably explains why ILC accounts for the disproportionately high number of malpractice claims for failure to diagnose breast cancer.
For more information on breast cancer or breast cancer litigation please contact Heffernan Research.