Your Pathology Report
What is a pathology report?
A pathologist is a doctor who specializes in diagnosing diseases by examining tissue from the body. You will probably never meet the pathologist, but samples of your breast tissue and lymph nodes, removed during needle biopsy or surgery, are sent to him /her for review. The pathologist prepares a summary report of his/ her findings, which is called the pathology report. The pathology report is usually written in highly technical medical language that may be difficult for the patient to understand. This section explains the complex terminology that may appear on a pathology report of the breast. Jane O’Brien routinely provides patients with a copy of all their pathology reports, explaining and discussing the report contents.
What will you find on a pathology report?
The report is broken down into several sections, including some information about the patient, such as the clinical diagnosis (suspected or known), the procedure, a description of what the specimen looks like to the naked eye (called macroscopic description), a description of what was seen under the microscope (microscopic description), and a pathologic diagnosis.
Your pathology report starts with general information such as your name, date of birth and hospital number, as well as your doctor’s name and the date of your surgery. This is usually followed by a description of the breast tissue before it’s looked at under a microscope. This section of the report is called the gross or macroscopic description and includes information about:
- The size, weight and appearance of the tissue
- Where it was in the breast before it was taken out
- How it was prepared for the microscope
Next follows the microscopic description, which points out all the features of the cancer seen under a microscope. Finally, there is a summary of the main points, sometimes in a list at the end of the report.
In the case of a breast cancer, the pathologist will describe the type of cell the cancer comes from, the tumour size and grade, whether the cancer cells have entered the lymph channels or blood vessels, information about surgical resection margins, and hormone receptor and Her2 status. Breast cancer pathology reports are one of the more complex pathology reports and can seem quite overwhelming at first glance.
This is generally not that important to you, the patient. It is a description of what the pathologist received and sees with the naked eye. In a biopsy, the specimen is likely a small, nondescript piece of tissue, in which case the pathologist may describe the colour, shape, feeling and size of the tissue. After a breast cancer surgery, large pieces of tissue and lymph nodes may be submitted and described in the report. This description might report the weight of the specimen, the presence of “inked” margins or sutures, which the surgeon adds so the pathologist can tell “which end is up” once the tissue is disconnected from the body. There may be mention of surgical clips or wires that were used by the surgeon to be sure that the suspicious area was removed. After a sentinel node biopsy, the gross description may say a lymph node is “hot”, which refers to the radioactive tracer that is used by the surgeon to locate the sentinel node, or that it is “blue”, due to the presence of dye that can also be used to locate the node. The pathologist often then describes how the tissue was divided up for further analysis.
This section contains the most useful information. Not every report goes through the microscopic diagnosis in the same order and some use different terms to describe the same thing. In this section we will discuss each part of the microscopic description in detail. Sometimes the tests are performed in different laboratories or take different lengths of time to complete, which can mean you may not get all the results at once. It is important to wait for all the results to best understand your situation.
Type of Breast Cancer
It seems simple: we are talking about breast cancer, so that’s what type it is. But it is not so simple. Almost all breast cancers arise from glandular tissue, making them adenocarcinomas (cancer of the glandular tissue); they are further named by where they start in the breast and how they appear under the microscope. To better understand this section, you need to have some knowledge of normal breast tissue. Breast tissue is composed of lobules, which produce milk; and ducts, which carry the milk to the nipple. Breast cancer starts in a duct or a lobule and this, along with its appearance under the microscope, determine the type of breast cancer it is. The type can dictate some of the treatment choices, although many types are treated similarly.
In addition to the type, the cancer can be non-invasive, which means it does not spread beyond the lobule or duct, or invasive, which means it has spread beyond the lobule or duct.
Types of Non-Invasive Breast Cancer
Ductal Carcinoma In Situ (DCIS)
DCIS is the most common type of non-invasive breast cancer and is sometimes called intraductal carcinoma. It is malignant (cancerous), and as it grows, the centre of the tumour starts to die because it has outgrown its blood supply. This area of dead tissue, called necrosis, can calcify, which can be detected on a mammogram. DCIS tumours are further identified by how the cells appear under the microscope, classifying them into subtypes. These subtypes are comedo, papillary, micropapillary, solid and cribiform. DCIS is described as low, intermediate or high grade.
Lobular Carcinoma in Situ (LCIS)
LCIS lesions rarely develop necrosis or calcifications, so are not often detected on mammograms. LCIS is not considered a true cancer, rather an accumulation of abnormal cells in the lobule. It is considered a risk factor for developing breast cancer in the future in either breast. LCIS is often found incidentally by the pathologist in a tissue specimen that was removed for another reason.
Types of Invasive Breast Cancers
Infiltrating Ductal Carcinoma (IDC)
IDC is the most common type of invasive cancer, accounting for about 85% of cases. This tumour starts in the duct and spreads beyond the duct into normal breast tissue.
Infiltrating Lobular Carcinoma (ILC)
ILC is less common, accounting for about 5-10% of cases. This tumour starts in the lobule and extends beyond the lobule into normal tissue.
Medullary carcinoma is rare, accounting for only 5% of all breast cancers. These cancers typically have a well defined boundary between the cancer cells and the normal cells.
Tubular carcinoma is a rare type of invasive breast cancer, accounting for about 2% of cases. Its name comes from the pathologist seeing a “tubular pattern” in 75% or more of the specimen. Tubular cancer does not typically spread to other areas of the body (called metastasize) and is associated with very good prognosis.
Mucinous carcinoma is a slow growing tumour. This tumour is also rare and is named for the mucin (protein and sugar compound) produced by and surrounding the tumour cells. These tumours also rarely spread to other parts of the body (metastasize) and also carry a very good prognosis.
Other Rare Subtypes
- Metaplastic – A rare variation of IDC
- Adenoid Cystic – Rare variation of a tumour that more commonly occurs in the salivary gland
- Paget’s Disease: development of red, weeping or crusty lesion on the breast tissue or nipple. While not a cancer itself, this is commonly associated with an underlying breast cancer
Histological grade is reported using the “Bloom Richardson Scale” or “Nottingham Score”. It is a combination of nuclear grade, mitotic rate, and tubule formation, which are characteristics of the tumour cells seen under a microscope that reflect/predict it’s aggressiveness. The scoring system is very detailed and you may see it on the report and be interested in what it means. In general, high grade tumours are more likely to recur when compared to low grade tumours.
- Nuclear Grade: a score is given from 1 to 3, based on the appearance of the nucleus of the cancer cells, with 1 being the closest to normal cells (better), 3 being the most variation (worse)
- Mitotic Rate: describes how quickly the cancer cells are multiplying or dividing using a 1 to 3 scale, 1 being the slowest, 3 the most rapid
- Tubule formation: this score represents the percent of cancer cells that are in tubule formation. A score of 1 means greater than 75% of cells are in tubule formation (better), a score of 3 is used when less than 10% of cells are in tubule formation (worse), a score of 2 is in between 10 and 75%
The three scores are then combined for a total score between 3 (1+1+1) and 9 (3+3+3). This score translates to a histological grade. You may see the three values and total score or just the final grade.
- Score of 3,4 or 5: Well differentiated or low grade (Grade 1)
- Score of 6 or 7: Moderately differentiated or intermediate grade (Grade 2)
- Score of 8 or 9: Poorly differentiated or high grade (Grade 3)
The size of the cancer is reported in centimetres. Tumour locations are often given based on the quadrant it was found in. Imagine the breast is divided with a “+” sign into 4 parts or quadrants. They are named upper inner quadrant (UIQ), upper outer quadrant (UOQ), lower outer quadrant (LOQ), lower inner quadrant (LIQ) and “axillary tail” is used to describe the breast tissue that extends towards the armpit.
It is not uncommon for the pathologist to find additional tumour(s) in the specimen that you did not know were there. If multiple tumours are found, the size and location of each will be noted. Multi-centric means there is more than one area of breast cancer in different quadrants of the breast. Multi-focal means more than one area has been seen but only in one quadrant of the breast.
Your report will give some information about the margins. These are the edges of the surgical specimen and the report will tell you how close the cancer comes to the edge. When performing cancer surgery, the surgeon attempts to remove the entire tumour and some normal tissue surrounding it. This area of “normal tissue” is important because any stray cancer cells may be included in this. If the edge (or margin) contains tumour, there may have been cancer cells left behind. The goal of surgery is to achieve a “clear margin”, that is, clear of any cancer cells. A “clean” or “clear” margin is defined as no tumour cells within 1-2 millimetres of the edge of the specimen. If the tumour cells are closer than this to the margin, additional surgery may be needed.
When wide local excision of a breast cancer is performed, a cylinder of breast tissue including the tumour is removed (see below) There is no further tissue superficially (the excision extends up to just below the skin) or deeply (the excision extends down to chest wall). The superficial and deep pathological margins are therefore not usually relevant as no further tissue can be taken from those margins. It is the radial margins (described in the pathology report as superior, inferior, medial and lateral) that are important, and if any of these margins are involved or inadequate, further surgery is likely to be advised.
When the pathologist examines the tumour and surrounding tissue available to them, they look at the tiny blood vessels and lymphatic drainage to see if any tumour cells have invaded them. This is different from the lymph nodes and would be reported as whether or not lymphatic or vascular invasion is seen. The presence of this may be a sign of a more aggressive tumour.
The lymph system is essentially the “housekeeping system” of the body. It is a network of vessels which connect lymph nodes. These nodes can vary in size, but are normally up to about 2 centimetres in width. They contain cells that clear bacteria and other foreign debris from the body. Lymph is a watery liquid that flows between cells in the body, picking up foreign debris and taking it into the lymph node for filtering and ultimately, elimination by the liver.
Cancer cells use the lymph system as a first step to travelling to other areas of the body. During breast cancer surgery, lymph nodes are removed and checked for the presence of cancer cells. This will be reported as the number of lymph nodes that contained cancer cells and how many were examined. For example, the report might state “ten benign lymph nodes (0/10)” (no cancer seen) or “tumour seen in ten of twelve lymph nodes (10/12).”
In most cases, sentinel lymph node biopsy will be used. This procedure involves injecting a radioactive tracer and a blue dye into the breast and allowing it to naturally drain to the lymph nodes. The first lymph nodes it travels to are called the sentinel node(s). The theory is that the cancer cells would travel the same path, so if cancer cells are not present in the sentinel node, it can be safely assumed that they have not spread into the lymph system. If the pathologist finds cancer cells in the sentinel node, a full axillary lymph node clearance/dissection is recommended.
Hormone Receptor Status
Hormone receptors for oestrogen and progesterone are present in high numbers in some breast cancers, making the growth of these tumours reliant on hormones. These tumours are referred to as hormone receptor positive, ER+/PR+, ER+/PR- or ER-/PR+. The receptors are present on the cancer cells and when the hormone attaches to the receptor, it allows the cancer cell to grow and divide. Hormone therapy can be used to interfere with these receptors, slowing or stopping tumour growth and preventing recurrence.
There is no universal standard for reporting the receptor status, so you may see anyone of the following:
- A percentage of the cells that reacted positive for receptors (from 0% to 100%)
- A number between 0 and 3, with 0 being no receptors and 3 being the most receptors. An Allred score is a combination of the percent positive and their intensity. The score is from 0-9, with 9 being the most strongly receptor positive
- Positive or negative
In the case of just a positive or negative result, the percentage should be requested. This is because research has shown that even tumours with very low positivity can benefit from hormone therapy, yet some labs report low results (<10%) as negative. Therefore, the only true negative is a result that is zero percent of receptors positive.
The Her-2 gene stimulates production of a protein found on the surface of breast cancer cells that tells the cells to grow and divide. In about 25% of breast cancers, there are too many copies of the gene or the protein is over expressed on the cell surface, causing the cancer to grow faster and be more aggressive. Breast tumours are routinely tested to see if they have too many copies of the gene or over express the protein. The immunohistochemistry (IHC) test looks for over expression of the protein and is reported as a number from 0 to +3. Zero and +1 are considered Her 2 negative, +2 is borderline and +3 is considered Her 2 positive.
The other two ways of measuring HER-2 are called CISH (chromogenic in situ hybridisation) and FISH (fluorescent in situ hybridisation) . These tests examine the tumour for extra copies of the Her 2 gene and are reported as positive or negative. These are regarded as the definitive tests on which the final decision regarding treatment will be made. HER-2 testing is normally only done on invasive breast cancer, so this may not be mentioned if you have ductal carcinoma in situ (DCIS) alone.
Her 2 positive tumours may be treated with medications, called monoclonal antibodies, targeting the Her 2 protein eg Herceptin.
Putting it all together
By understanding the basics of your pathology report, you will be better able to discuss your treatment options with your healthcare team. Remember that all the information in the pathology report is considered together when deciding about which treatments to offer you and their likely benefits. No one piece of information should be looked at on its own – it always needs to be related to all the other information.