What do my Biopsy results mean?

September 24th, 2021

After your breast mass has been biopsied and sent off to the pathologist, it usually takes approximately 7-10 days for the biopsy results to come back. During that time, the pathologist performs a detailed analysis of the biopsy under the microscope to specifically determine what cells are involved, is there actually cancer and has cancer had the ability to spread (invasive). In this article, we will discuss the common pathologic results that return back regarding your breast mass.


DCIS stands for Ductal Carcinoma In Situ. The majority of breast cancer is called ductal cancer meaning it derives from the cells that make up the ducts or tubes involved in breastfeeding. The breast is made up a complex network of glands and ducts that coalesce and terminate in the nipple. As milk is produced, it is shuttled into these ducts and eventually exit from the nipple. It is from the cells of these ducts that most breast cancers arise. To the pathologist, he or she can differentiate under the microscope of what a normal ductal cell looks like and what an abnormal ductal cell looks like. Think of normal ductal cells becoming ZOMBIES, that is what cancer is. DCIS is considered the earliest form of breast cancer. DCIS is noninvasive, meaning it has not spread out of the milk duct to invade other parts of the breast. While DCIS is not invasive, it does require surgical treatment to prevent the condition from becoming invasive. All surgical options will be discussed in later articles but in general, surgery for many of these biopsy results will either be a lumpectomy or mastectomy.

IDC Breast Cancer

IDC stands for Infiltrating or Invasive Ductal Carcinoma. In IDC, the same ductal cells that were just discussed in breastfeeding now have the ability to spread. This distinction between DCIS and IDC can only be seen by the pathologist under the microscope. What the pathologist typically sees now is that the abnormal ductal cells are now found outside of the ducts giving them the ability to spread. ZOMBIE cells are now seen both inside a piece of ductal tissue as well as outside the ductal tissue.

LCIS Breast Cancer

LCIS stands for Lobular Carcinoma In-Situ. In lobular carcinoma, abnormal cells start growing in the lobules, the milk-producing glands at the end of breast ducts.

In situ or “in its original place” means that the abnormal growth remains inside the lobule and has not developed the ability to spread yet. LCIS is not true breast cancer. Rather, LCIS is an indication that a person is at higher-than-average risk for getting breast cancer at some point in the future. Some have argued for it to be called something different like “lobular neoplasia”. It tends to be diagnosed as a result of a biopsy performed on the breast for some other reason since LCIS cannot be seen by a mammogram, ultrasound, or MRI.

ILC Breast Cancer

ILC stands for Infiltrating or Invasive Lobular Carcinoma. The cells that make up the milk-producing lobules (glands) of the breast have become abnormal and can be seen both inside and outside of the lobules. Much like Invasive Ductal Carcinoma (IDC), these ZOMBIES cells have gained the ability to spread and can be seen under the microscope by the pathologist. ILC is the second most common invasive breast cancer behind IDC and comprises only 10% of all invasive cancer with IDC making up 80%. ILC typically occurs later in age with 2/3 of patients generally over the age of 55.


Paget’s disease is a rare form of breast cancer in which cancer cells are seen at or around the nipple. The typical presentation includes visual changes to the skin of the nipple and areola. Cancer usually affects the ducts of the nipple first, then spreads to the nipple surface and the areola. The nipple and areola often become scaly, red, itchy, and irritated. A skin biopsy is then usually sent off by the breast surgeon and then examined under the microscope by the pathologist. Pagets only accounts for 5% of all breast cancer cases in the United States. The unusual changes in the nipple and areola are often the first indication that breast cancer is present somewhere since over 90% of the time, the Paget’s disease at the nipple is correlated with some underlying cancer in the breast itself.

Inflammatory Breast Cancer

Inflammatory Breast Cancer can be simplified as any breast cancer with associated skin changes. That means there is a breast cancer mass and the mass has also affected the skin. The skin will demonstrate changes that are usually described as skin thicking, skin dimpling, or a “peau de orange” look. “Peau de orange” means the skin of an orange. Under the microscope, the pathologist may see cancer cells in the skin or the lymphatics of the skin.

Phyllodes Tumor

Phyllodes tumors are not cancers and only represent 1% of all tumors that are found in the breast. These tumors are benign and do not have the ability to spread. They are however troublesome since they grow quickly and can over a short period of time, double their size. Resection of Phyllodes tumor should also include a margin since they have a propensity to come back.

What about these other “tests” I see on my pathology results??

  • ER/PR negative or positive
    Specific staining tests can be performed on the breast cancer specimen looking for hormone receptors. If receptors are seen, they are labeled as either ER or PR positive with ER/PR denoting estrogen and progesterone respectively. A certain percentage can also be attributed to positive results further defining how many of the abnormal cells exhibit the hormone receptors. A positive ER/PR diagnosis portends a better diagnosis since cancer feeds and grows in the presence of estrogen or progesterone. This is a favorable result since the additional treatment of cancer can be achieved with hormone-blocking drugs such as Tamoxifen. A newer class of drug called aromatase inhibitors block the production of hormones can also be used. Common aromatase inhibitors include anastrozole (Arimidex), exemestane (Aromasin), letrozole (Femara).
  • Her2
    HER2 (human epidermal growth factor receptor 2) is a gene that can play a role in the development of breast cancer. Your pathology report should include information about HER2 status, which tells you whether or not HER2 is playing a role in cancer. Normally, HER2 receptors help control how a healthy breast cell grows, divides, and repairs itself. But in about 25% of breast cancers, the HER2 gene does not work correctly and contributes to cancer growing in an uncontrolled manner. Breast cancers with HER2 gene amplification or HER2 protein overexpression are called HER2-positive on the pathology report. HER2-positive breast cancers tend to grow faster and are more likely to spread and come back. Her2 is important in the additional treatment of breast cancer since trastuzumab (Herceptin) works by blocking the faulty HER2 receptor, blocking the signals that tell the abnormal cell to keep growing.
  • Ki67
    Normal cells exhibit a normal cell cycle that involves dividing and then resting so that there is not constant growth. Abnormal cancerous cells constantly divide and replicate and do not stop doing so which makes them cancers or ZOMBIE cells. Therefore if there was some way to see how many of the cells were rapidly dividing, we could see how aggressive the cancer is. Ki-67 is a normal protein that is seen when a cell is dividing. A test can look at how many of the cells are actually replicating which is quantitated with a percentage. A higher Ki-67 means that more of the cells are growing and dividing whereas a lower percentage means the vice versa. A higher Ki-67, therefore, predicts a more aggressive faster-growing cancer.