Skip to main content
An official website of the United States government

Breast Ductal Carcinoma Study

What is breast cancer?

This cancer starts in the tissues of the breast. Breast cancer is the most frequently diagnosed cancer and the second cause of cancer deaths in women. In 2010, 207,090 women were estimated to have been diagnosed with invasive breast cancer in the United States and approximately 40,000 women were estimated to have died of their disease.1 

Men can also have breast cancer, although male breast cancer is rare. In 2010, 1,970 American men were estimated to have been diagnosed and 390 were estimated to have died of breast cancer.1 Due to early detection through use of mammograms and improvements in treatment, breast cancer deaths have steadily decreased since the 1990s. Additional information on breast cancer.

TCGA focused mainly on two types of invasive breast cancer: ductal carcinoma and lobular carcinoma. Invasive ductal carcinoma is the most common type of breast cancer. It comprises about 6585% of all breast cancer and develops in the milk ducts of the breast. About 10% of all cases of advanced breast cancer2 are invasive lobular breast carcinoma. This cancer develops in the breast milk-producing lobules or glands.

What have TCGA researchers learned about breast cancer?

  • The cancer can be categorized into four molecular subtypes: HER2-enriched, Luminal A, Luminal B, and Basal-like. Each subtype is associated with a unique panel of mutated genes.
  • Basal-like subtype shares many genetic features with high-grade serous ovarian cancer, suggesting that the cancers have a common molecular origin and may share therapeutic opportunities, such as:
    • A drug that inhibits blood vessel growth, cutting off the blood supply to the tumor.
    • Bioreductive drugs, which are inactive drugs that become toxic to cancer cells under low oxygen conditions.