Ductal carcinoma is a form of breast cancer where cancerous cells grow in breast ducts, the tubes that carry breast milk from the breast lobules, where it is secreted to the nipple. Ductal carcinoma is the most common form of breast cancer, accounting for about 80 percent of diagnoses in the United States, according the American Cancer Society (ACS). Ductal carcinoma is usually diagnosed in women, although it is also the most common type of breast cancer diagnosed in men.

• There are two main types of ductal carcinoma:
  
  Ductal carcinoma in situ (also called DCIS or intraductal carcinoma). Typically, a noninvasive form of ductal carcinoma, in which the disease does not spread outside the duct where it began. Although it can sometimes become invasive and spread outside the duct, DCIS may be considered a precancerous condition.
  
  
• Invasive ductal carcinoma (also called infiltrating carcinoma). This type of ductal carcinoma develops when abnormal cells grow within the breast duct and then spread through the membrane that lines the bottom of the cells to tissue outside the duct. Left untreated, invasive ductal carcinoma can spread to other parts of the body.

DCIS is usually diagnosed during regularly scheduled mammograms. Invasive ductal carcinoma often forms a hard lump. It can sometimes be found during monthly breast self-examinations, a breast examination by a physician or other healthcare provider, or during a mammogram, which frequently can detect cancers too small to be felt. 

To diagnose breast cancer, a biopsy is performed in which part or all of the abnormal mass is removed and analyzed by a pathologist who views the specimen under a microscope. If a pathologist finds the tumor to be malignant (cancerous), additional tests may be ordered to provide additional information about the tumor.

To determine the stage of cancer, an oncologist will consider the size of the malignant tumor, and any possible spread of the cancer to the lymph nodes and to other organs or tissues. Staging cancer helps an oncologist identify the best treatment options for ductal carcinoma. This may include surgery, radiation therapy, chemotherapy, therapy to block the actions of certain hormones and biological therapy.

Overall survival rates for breast cancer are quite high when the disease is detected and treated in its earliest stages. When breast cancer progresses undetected to later stages, the survival rates drop and the treatments are more aggressive. Survival rates for breast cancer have improved over the past two decades. The increased survival rates are related to the earlier detection and treatment of breast cancer, and increased awareness of the issue in the general population.