No two breast cancers are the same. At Penn Medicine Lancaster General Health, we understand that learning about each individual cancer is the key to effective breast cancer treatment.

Our pathologists (doctors who study tissue) have a deep understanding of breast cancer. They identify the cancer type and the tumor’s unique characteristics to provide a personalized and precise breast cancer diagnosis.

How We Determine Breast Cancer Type

Breast cancer occurs when healthy cells change and grow out of control, and there are many types of breast cancer. To identify the type, we look at where the cancer began and whether it has spread.

Most breast cancers begin in the breast ducts, which carry milk to the nipples (ductal cancers). Other breast cancers form in the breast lobules, the glands that produce milk (lobular cancers).

Both ductal cancers and lobular cancers can grow into surrounding breast tissue or even spread other areas of the body (called metastatic breast cancer). Cancer that grows into nearby breast tissue is considered invasive. Cancer that has not grown into surrounding tissue is called noninvasive.

Noninvasive Breast Cancer (Ductal Carcinoma in Situ)

Ductal carcinoma in situ (DCIS) is breast cancer located in the milk ducts that has not spread to nearby breast tissue. About 20 percent of all diagnosed breast cancers are DCIS. While it is not life-threatening, a DCIS diagnosis increases your cancer risk for recurrence (coming back) or developing a new breast cancer.

Invasive Breast Cancer

Breast cancer is considered invasive, or infiltrating, when it spreads to nearby breast tissue. There are different types of invasive cancers, including:

Male Breast Cancer

Men can develop breast cancer, but it is rare. Most breast cancer in men begins in the ducts and is typically discovered at an advanced stage. Since men are not screened for breast cancer, the first sign of cancer may be a lump or change in breast shape.

Other Characteristics of Breast Cancer

When we remove and study a small piece of your breast tissue (biopsy), we also test the cancer cells to learn more about them. We examine your cells for hormone receptors and protein receptors, which can explain what’s making the cancer cells grow. Depending on those test results, we may use specialized therapies to personalize your treatment.

Hormone Receptors

Some breast cancers use the hormones estrogen and progesterone to grow. Those cancer cells have receptors that “feed” on the hormones. These tumors are considered hormone receptor-positive (HR+). About 80 percent of all breast cancers are HR+.

Breast cancer may test positive for estrogen (ER+), progesterone (PR+) or both (ER/PR+). We use hormone therapy to slow the growth of HR+ cancers. Learn more about hormone-positive breast cancer.

HER2 Status

We test breast cancer tissue for a protein called HER2, or human epidermal growth factor receptor 2. All breast cells have HER2 protein (made by the HER2 gene). This protein helps breast tissue grow and repair at a normal rate. If an excess of HER2 protein forms, the cells begin to grow too rapidly, leading to a tumor.

Breast cancer that tests positive for HER2 may grow quickly. Special medication, called targeted therapy, treats HER2-positive cancer by slowing or stopping tumor growth. Learn more about HER2-positive breast cancer.

Triple Negative Breast Cancer

Triple negative breast cancer tests negative for both hormone receptors and HER2. It does not use estrogen, progesterone or HER2 to grow. About 10 to 15 percent of all breast cancers are triple negative. Learn more about triple negative breast cancer.

Request an Appointment

To make an appointment at the Ann B. Barshinger Cancer Institute, call 717-544-9400 or request a callback using our online form.

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