The purpose of a breast biopsy is to confirm whether breast cancer is present. Once the tissue samples are taken, a doctor called a pathologist will examine them under a microscope and compile their findings in a pathology report. This report provides crucial information about what is happening in your breast and will guide treatment options if cancer is detected.
What Information Does a Pathology Report Provide?
Pathology reports can be difficult to understand, especially since pathologists sometimes describe the findings using scientific terms. However, the doctor who requested the biopsy and the oncologist will know what each item means and which actions to take next. Most breast pathology reports contain the following sections:
Specimen Description
This includes details about the tissue sample, such as the type of tissue and the area it was taken from (e.g., breast, lymph nodes).
Clinical History and Pre-pathology Diagnosis
This section provides information about what was found, details about the biopsy or surgery, and sometimes other relevant medical history. It also includes the doctor's initial diagnosis.
Gross (Macroscopic) Description
This section summarizes what the removed tissues look like to the visible eye (before they are viewed under a microscope), including their size, weight, color, texture, and any other distinguishing features.
Microscopic Description
This section provides a detailed summary of the tissues based on their appearance under a microscope. If cancer cells are found, the pathologist will describe whether the cells are contained to the breast or have spread.
- Noninvasive cancer, called in-situ carcinoma, remains in the breast's milk ducts or lobules.
- Cancerous cells that spread beyond the ducts or lobules into other tissues are called invasive or infiltrating carcinoma.
Tumor Margin
The margin refers to the area surrounding the suspected cancer removed during a biopsy or surgery. A positive or involved margin indicates the presence of cancer cells on the edges of the tissue sample, suggesting that they are likely still present in the body. A negative margin indicates the absence of cancer cells in the outer edge of the tissue sample. A "close" margin means that cancer cells are not present at the edge but are close to it, which may require the removal of a wider area of tissue.
Final Diagnosis
If cancer is found, the final diagnosis will summarize the most important characteristics of the breast cancer. This section typically describes the type of breast cancer, tumor grade, lymph node involvement, hormone receptor status, and HER2 status.
Types of Breast Cancer
The report will name the type of cancer found. If lobular carcinoma in situ (LCIS) is listed, the diagnosis is not cancer. LCIS is an overgrowth of abnormal cells contained in the milk glands or lobules, indicating an increased risk of developing invasive cancer in the future.
Most patients have one of the following types of breast cancer listed in the pathology report if breast cancer was found in the tissue samples:
- Ductal Carcinoma In Situ (DCIS): Cancer remains in the milk ducts and is not invasive.
- Invasive Ductal Carcinoma (IDC): This is the most common type of breast cancer. It develops in the milk ducts and grows into the surrounding breast tissues.
- Invasive Lobular Carcinoma (ILC): Cancer starts inside the lobules and grows into the surrounding breast tissues.
Less common types of breast cancer may be described as:
- Inflammatory breast cancer
- Paget’s disease
- Phyllodes tumor
- Angiosarcoma
Tumor Grade
The breast cancer grade indicates how closely the cancer cells resemble healthy breast cancer cells and how quickly the tumor is likely to grow and spread. The pathologist assesses three main features to determine the abnormality of the cancer cells and tissue:
- The presence of normal breast ducts in the tumor tissue
- The size and shape of the breast tumor cells
- How fast the tumor cells are growing and dividing (also called the mitotic rate or Ki-67)
Grading scales may use the numeric Scarff-Bloom-Richardson (SBR) system or one of the following descriptions: well differentiated, moderately differentiated, or poorly differentiated.
- Grade 1 or well-differentiated: Cells closely resemble healthy breast cells and have a slower growth rate.
- Grade 2 or moderately differentiated: Cells are somewhat abnormal, with features between well-differentiated (normal) and poorly-differentiated (abnormal) cells.
- Grade 3 or poorly differentiated: Cells are highly abnormal and typically fast-growing.
Vascular Invasion and Lymph Node Involvement
Vascular invasion refers to the spread of cancer cells through the lymph channels or breast blood vessels. A pathologist will indicate whether or not this has occurred by listing it on the report as present or absent.
Lymph nodes act as filters for the lymph channels and can capture cancer cells. Lymph nodes without cancer are considered negative, while those with cancer cells are considered positive.
The presence of cancer cells in each lymph node can be categorized as:
- Microscopic: A few cancer cells are only visible under a microscope
- Gross: Many cancer cells can be seen or felt without a microscope
- Extracapsular Extension: Cancer cells that have spread beyond the lymph node's capsule or wall
Hormone Receptor Status
The hormone receptor status of breast cancer refers to whether the breast cancer cells are fueled by estrogen and/or progesterone due to special proteins inside the tumor cells called hormone receptors. A hormone receptor status is either hormone receptor-positive or hormone receptor-negative. Your cancer could be positive for one type of receptor and negative for the other.
You may see one of the following in your report:
- A percentage between 0 and 100% indicates the number of receptor-positive cells out of 100 cells tested.
- An "Allred score," a combination of the percent of receptor-positive cells and their intensity. Scores range from 0-8. The higher the score, the more hormone receptors were found.
- The word positive or negative.
HER2 Status
HER2 status is another section of the breast profile included in the pathology report. HER2 is a protein that appears on the surface of breast cells but may be overexpressed in some cancers. The report will indicate a HER2-positive status if present.
Pathology Report is Used for Breast Cancer Staging
Cancer staging helps guide treatment decisions and gives insight into possible outcomes. Staging also organizes information using a common language that all members of your care team can understand. The specific stage of cancer is not defined in the pathology report. However, the information in the report will assist the oncologist in making this determination.
Breast cancer is staged using the TNM system. TNM stands for:
- T = Tumor size
- N = Lymph Node status (the number and location of lymph nodes with cancer)
- M = Metastases (whether or not the cancer has spread to other parts of the body)
Numbers or letters after T, N, and M provide more detailed information about each characteristic. Higher numbers mean the cancer is more advanced.
Based on the TNM results, a stage is determined, represented by a number on a scale of 0 to IV (4). Stage 0 refers to non-invasive cancers that stay within their original location, while stage IV refers to invasive cancers that have spread beyond the breast to other parts of the body.
Learn more about breast cancer stages.
Next Steps After a Breast Cancer Diagnosis
After a breast cancer diagnosis, you are likely to consult with a breast cancer surgeon and a medical oncologist. A radiation oncologist may also be included in the treatment plan. Our team is here to help you with any necessary radiation therapy. Remember, you can choose a location near your home or work for this treatment. We offer radiation therapy locations with the latest technologies throughout the Atlanta area.
