The only sure way to find out if a breast abnormality is cancer is to have a biopsy. A surgeon or radiologist will remove a sample of suspicious tissue and send it to a pathologist, who examines it under a microscope and makes a diagnosis. The pathologist will send a report with the diagnosis back to your physician, who will explain the report to you and answer any questions you may have.
A pathology report is written in medical language, and the technical wording on it can be very confusing. This guide will help you understand the report and your diagnosis.
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The majority of breast cancers are invasive ductal carcinomas (70% - 80%), followed by lobular carcinomas and other rare types of breast cancer.
Non-invasive cancer stays put in its original location and does not invade surrounding tissue.
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DCIS is cancer inside a milk duct of the breast that has not broken out and invaded into adjacent tissue.
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LCIS is an abnormality confined to the milk-producing lobules. It is not cancer, but is a risk factor for development of breast cancer in the future.
Invasive means the cancer has invaded surrounding healthy breast tissue.
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IDC is cancer that starts in the milk duct but grows through the duct and invades into adjacent tissue. This is the most common form of breast cancer.
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ILC is cancer that invades surrounding normal breast tissue and shows morphologic features similar to those of normal lobular cells.
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Your doctor will measure the size of a tumor at its widest point. The standard unit of measurement is centimeters (cm). Tumor size can range from 1 mm or less to 5 cm or more. Measuring tumor size is important in determining the stage of the cancer.
Tumor grade is a description of how the cancer cells look compared to normal cells under a microscope. Experts compare the appearance of the tumor cells to healthy breast cells to determine the grade.
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Cancer cells look slightly different from normal cells and are usually slow growing. Grade 1 is also referred to as "low grade" or "well-differentiated".
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Cancer cells do not look like normal cells and grow faster than normal. Grade 2 is also referred to as "intermediate grade" or "moderately differentiated".
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Cancer cells have markedly atypical appearance and grow rapidly. Grade 3 is also referred to as "high grade" or "poorly differentiated."
Your surgeon will remove an extra area of normal tissue around your tumor to make sure the cancer is completely removed. This extra tissue is called the margin of resection. The pathologist measures the distance from the cancer cells to the outer edges of the tissue and places the results in the pathology report. The standard negative measurement is controversial but one-two millimeters of healthy tissue beyond the edge of the malignant tumor is usually accepted as negative.
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Cancer cells reach the edge of the tissue sample. Some cancer may have been left in the breast and further surgery may be required.
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Cancer cells do not reach the outer edge of the tissue. Usually no more surgery is needed.
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Uncertainty about whether the margin is positive or negative. More surgery may be needed.
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The lymph nodes are responsible for filtering waste products from the blood before it circulates back to the rest of the body. If the lymph nodes under your arm contain tumor cells, there is a high risk the cancer could spread to the rest of your body. Your pathology report will contain information about the status of your lymph nodes.
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Hormone receptors are cell proteins found on the surface of some cancer cells. These receptors receive signals from the hormones estrogen and progesterone that tell the cancer cells to divide and grow. A cancer is ER+ if it has estrogen receptors and PR+ if it has progesterone receptors. Patients with ER+ and/or PR+ tumors will need hormone therapy to reduce the amount of these hormones in the body and slow down tumor cell growth. Your pathology report will tell you if you have a tumor that is ER+ or PR+.
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The HER2 protein usually controls how a breast cell grows and divides, but in some forms of breast cancer this gene becomes abnormal and makes too many copies. When this happens, the breast cells grow and divide more rapidly. Breast cancers with excess HER2 genes are called HER2-positive. HER2-positive breast cancers are more aggressive and have a greater chance of spreading than HER2-negative cancers. We can determine the HER2 positivity by immunohistochemical staining or genomic testing (FISH). However, HER2-positive breast cancers respond well to targeted treatments that prevent the protein from stimulating tumor growth. Your pathology report will tell you if you are HER2-positive or HER2-negative.
Cell growth rate is the percentage of cancer cells within a tumor that are actively growing and multiplying. Ki-67 is a protein in cells that increases when the cells are multiplying. The more cells that are positive for Ki-67, the higher the cell growth rate.
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The pathologist will also look closely at the small caliber blood and lymph vessels around the tumor to determine if any cancer cells have invaded them. When cancer cells invade these vessels, it is called a lymphovascular invasion.
Oncotype DX is a genomic test for breast cancer that evaluates the patient’s risk of recurrence and likely response to chemotherapy. Oncotype DX is recommended for patients with early-stage disease who are ER+ and HER2-. The test analyzes the activity of 21 genes that have been identified as biomarkers for breast cancer. Based on the results of the test, the patient receives a Recurrence Score between 0 and 100. A low score means the patient has a low risk of recurrence and may not benefit from chemotherapy. A high score means the patient has a high risk of recurrence and would likely benefit from chemotherapy treatment. MammaPrint is another less common genomic test sometimes used.
Extensive research effort has been put on the development of additional molecular tests that can be used to predict the clinical course of the disease or response to different therapy options. Many of these are tested in clinical trials.
For patients with metastatic breast cancer, your doctor may approach about conducting a genetic testing of your tumors. These tests are different from testing your normal cells for example like BRCA to understand the risk of development of the breast cancer. Rather these tests are conducted to lead the physicians to determine if you are appropriate for certain targeted therapy or immunotherapy. These treatments are generally under tested in clinical trials. It is important to discuss with your doctor whether you are appropriate for your tumor to be tested for genomic testing.
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