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Invasive Ductal Carcinoma Versus Ductal Carcinoma In-Situ

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Carolyn Vachani, RN, MSN, AOCN
Last Modified: January 10, 2006

Dear OncoLink "Ask the Experts,"
I am trying to research the differences between invasive ductal carcinoma and DCIS (ductal carcinoma in-situ) to determine which form of breast cancer from which our client is suffering. I know that she has cancer in 12 of 21 lymph nodes and that the cancer is invasive. Please provide me with any information you may have to help in my determination.

Carolyn Vachani, RN, MSN, AOCN, OncoLink's Nurse Educator responds:

You have inadvertently answered you own question by saying the cancer has spread to 12 of 21 nodes. Ductal carcinoma in-situ (DCIS) is a noninvasive disease/cancer, meaning it does not spread past the original duct. The frequency of DCIS metastasizing into the patient's lymph nodes is less than 1%. Therefore, having lymph nodes involved really points to an invasive cancer. "Invasive" implies that the tumor itself has spread through the cell's membrane and has infiltrated the local lymphatic tissue.

The other issue is whether this invasive cancer you speak of is ductal, lobular or one of the less common types. The most common type of breast cancer is ductal carcinoma, accounting for approximately 85% of breast cancers. Lobular breast cancers make up about 5 to 10% of all breast cancers. Both types are treated similarly and have similar prognoses.