How Is Breast Cancer Diagnosed?
Although breast cancer is sometimes found after symptoms appear, many women with early breast cancer have no symptoms. This is why getting the recommended screening tests (as described in “Can breast cancer be found early?”) before any symptoms develop is so important.
If something suspicious is found during a screening exam, or if you have any of the symptoms of breast cancer described below, your doctor will use one or more methods to find out if the disease is present. If cancer is found, other tests will be done to determine the stage (extent) of the cancer.
Signs and symptoms
Although widespread use of screening mammograms has increased the number of breast cancers found before they cause any symptoms, some breast cancers are not found by mammogram, either because the test was not done or because, even under ideal conditions, mammograms do not find every breast cancer.
The most common sign of breast cancer is a new lump or mass. A painless, hard mass that has irregular edges is more likely to be cancerous, but breast cancers can be tender, soft, or rounded. For this reason, it is important that any new breast mass or lump be checked by a health care professional experienced in diagnosing breast diseases.
Other possible signs of breast cancer include:
* swelling of all or part of a breast (even if no distinct lump is felt)
* skin irritation or dimpling
* breast or nipple pain
* nipple retraction (turning inward)
* redness, scaliness, or thickening of the nipple or breast skin
* a discharge other than breast milk
Sometimes a breast cancer can spread to underarm lymph nodes and cause a lump or swelling there, even before the original tumor in the breast tissue is large enough to be felt.
Medical history and physical exam
If you have any signs or symptoms that might be due to breast cancer, be sure to see your doctor as soon as possible. Your doctor will ask you questions about your symptoms, any other health problems, and possible risk factors for benign breast conditions or breast cancer.
Your breasts will be thoroughly examined for any lumps or suspicious areas and to feel their texture, size, and relationship to the skin and chest muscles. Any changes in the nipples or the skin of your breasts will be noted. The lymph nodes in the armpit and above the collarbones may be palpated (felt), because enlargement or firmness of these lymph nodes might indicate spread of breast cancer. Your doctor may also probably do a complete physical exam to judge your general health and whether there is any evidence of cancer that may have spread.
If breast symptoms and/or the results of your physical exam suggest breast cancer might be present, more tests will likely be done. These might include imaging tests, looking at samples of nipple discharge, or doing biopsies of suspicious areas.
Imaging tests used to evaluate breast disease
Imaging tests use x-rays, magnetic fields, sound waves, or radioactive substances to create pictures of the inside of your body. Imaging tests may be done for a number of reasons, including to help find out whether a suspicious area might be cancerous, to learn how far cancer may have spread, and to help determine if treatment is working.
Although mammograms are mostly used for screening, they can also be used to examine the breast of a woman who has a breast problem. This can be a breast mass, nipple discharge, or an abnormality that was found on a screening mammogram. In some cases, special images known as cone views with magnification are used to make a small area of abnormal breast tissue easier to evaluate.
A diagnostic mammogram can show:
* That the abnormality is not worrisome at all. In these cases the woman can usually return to having routine yearly mammograms.
* That a lesion (area of abnormal tissue) has a high likelihood of being benign (not cancer). In these cases, it is common to ask the woman to come back sooner than usual for her next mammogram, usually in 4 to 6 months
* That the lesion is more suspicious, and a biopsy is needed to tell if it is cancer.
Even if the mammograms show no tumor, if you or your doctor can feel a lump, a biopsy is usually needed to make sure it isn’t cancer. One exception would be if an ultrasound exam finds that the lump is a simple cyst (a fluid-filled sac), which is very unlikely to be cancerous.
Digital mammograms: A digital mammogram (also known as a full-field digital mammogram, or FFDM) is like a standard mammogram in that x-rays are used to produce an image of your breast. The differences are in the way the image is recorded, viewed by the doctor, and stored. Standard mammograms are recorded on large sheets of photographic film. Digital mammograms are recorded and stored on a computer. After the exam, the doctor can look at them on a computer screen and adjust the image size, brightness, or contrast to see certain areas more clearly. Digital images can also be sent electronically to another site for a remote consult with breast specialists. Many centers do not offer the digital option, but it is becoming more widely available with time.
Because digital mammograms cost more than standard mammograms, studies are now looking at which form of mammogram will benefit more women in the long run. Some studies have found that women who have a FFDM have to return less often for additional imaging tests because of inconclusive areas on the original mammogram. A recent large study found that a FFDM was more accurate in finding cancers in women younger than 50 and in women with dense breast tissue, although the rates of inconclusive results were similar between FFDM and film mammograms. It is important to remember that a standard film mammogram also is effective for these groups of women, and that they should not miss their regular mammogram if a digital mammogram is not available.
Computer-aided detection and diagnosis (CAD): Over the past 2 decades, computer-aided detection and diagnosis (CAD) has been developed to help radiologists detect suspicious changes on mammograms. This can be done with standard film mammograms or with digital mammograms.
Computers can help doctors identify abnormal areas on a mammogram by acting as a second set of “eyes.” For standard mammograms, the film is fed into a machine which converts the image into a digital signal that is then analyzed by the computer. Alternatively, the technology can be applied to a digital mammogram. The computer then displays the image on a video screen, with markers pointing to areas that the radiologist should check especially closely.
It’s not yet clear how useful CAD is. Some doctors find it helpful, but a recent large study found it did not significantly improve the accuracy of breast cancer detection. It did, however, increase the number of women who needed to have breast biopsies. Further research is needed.
Magnetic resonance imaging (MRI) of the breast
MRI scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed and then released in a pattern formed by the type of body tissue and by certain diseases. A computer translates the pattern into a very detailed image of parts of the body. A contrast liquid called gadolinium is often injected into a vein before or during the scan to show details better.
MRI scans can take a long time — often up to an hour. You have to lie inside a narrow tube, which is confining and may upset people with claustrophobia (a fear of enclosed spaces). The machine also makes loud buzzing and clicking noises that you may find disturbing. Some places will give you headphones with music to block this out. MRIs are also expensive, although insurance plans generally pay for them in some situations, such as once cancer is diagnosed.
Although MRI machines are quite common, they need to be specially adapted to look at the breast. It’s important that MRI scans of the breast be done on one of these specially adapted machines.
MRI can be used along with mammograms for screening women who have a high risk of developing breast cancer, or it can be used to better examine suspicious areas found by a mammogram. MRI is also used for women who have been diagnosed with breast cancer to better determine the actual size of the cancer and to look for any other cancers in the breast.
If an abnormal area in the breast is found, it can often be biopsied using an MRI for guidance. This is discussed in more detail in the “Biopsy” section.
Ultrasound, also known as sonography, uses sound waves to outline a part of the body. For this test, a small, microphone-like instrument called a transducer is placed on the skin (which is often first lubricated with ultrasound gel). It emits sound waves and picks up the echoes as they bounce off body tissues. The echoes are converted by a computer into a black and white image that is displayed on a computer screen. This test is painless and does not expose you to radiation.
Ultrasound has become a valuable tool to use along with mammography because it is widely available and less expensive than other options, such as MRI. The use of ultrasound instead of mammograms for breast cancer screening is not recommended. Usually, breast ultrasound is used to target a specific area of concern found on the mammogram. Ultrasound helps distinguish between cysts (fluid-filled sacs) and solid masses and sometimes can help tell the difference between benign and cancerous tumors.
Ultrasound may be most helpful in women with very dense breasts. Clinical trials are now looking at the benefits and risks of adding breast ultrasound to screening mammograms in women with dense breasts and a higher risk of breast cancer.
This test, also called a galactogram, sometimes helps determine the cause of nipple discharge. In this test a very thin plastic tube is placed into the opening of the duct in the nipple that the discharge is coming from. A small amount of contrast medium is injected, which outlines the shape of the duct on an x-ray image and shows if there is a mass inside the duct.
Newer imaging tests
Newer tests such as scintimammography and tomosynthesis are not used commonly and are still being studied to determine their usefulness. They are described in the section, “What’s new in breast cancer research and treatment?”
These tests may be done for the purposes of research, but they have not yet been found to be helpful in diagnosing breast cancer in most women.
Nipple discharge exam
If you are having nipple discharge, some of the fluid may be collected and looked at under a microscope to see if any cancer cells are in it. Most nipple discharges or secretions are not cancer. In general, if the secretion appears milky or clear green, cancer is very unlikely. If the discharge is red or red-brown, suggesting that it contains blood, it might possibly be caused by cancer, although an injury, infection, or benign tumors are more likely causes.
Even when no cancer cells are found in a nipple discharge, it is not possible to say for certain that a breast cancer is not there. If a patient has a suspicious mass, it will be necessary to biopsy the mass, even if the nipple discharge does not contain cancer cells.
Ductal lavage and nipple aspiration
Ductal lavage is an experimental test developed for women who have no symptoms of breast cancer but are at very high risk for the disease. It is not a test to screen for or diagnose breast cancer, but it may help give a more accurate picture of a woman’s risk of developing it.
Ductal lavage can be done in a doctor’s office or an outpatient facility. An anesthetic cream is applied to numb the nipple area. Gentle suction is then used to help draw tiny amounts of fluid from the milk ducts up to the nipple surface, which helps locate the ducts’ natural openings. A tiny tube (called a catheter) is then inserted into a duct opening. Saline (salt water) is slowly infused into the catheter to gently rinse the duct and collect cells. The ductal fluid is withdrawn through the catheter and sent to a lab, where the cells are looked at under a microscope.
Ductal lavage is not considered appropriate for women who aren’t at high risk for breast cancer. It is not clear if it will ever be useful. The test has not been shown to detect cancer early. It is more likely to be helpful as a test of cancer risk rather than as a screening test for cancer. More studies are needed to better define the usefulness of this test.
Nipple aspiration also looks for abnormal cells developing in the ducts, but is much simpler, because nothing is inserted into the breast. The device for nipple aspiration uses small cups that are placed on the woman’s breasts. The device warms the breasts, gently compresses them, and applies light suction to bring nipple fluid to the surface of the breast. The nipple fluid is then collected and sent to a lab for analysis. As with ductal lavage, the procedure may be useful as a test of cancer risk but is not appropriate as a screening test for cancer. The test has not been shown to detect cancer early.
During a biopsy, the doctor removes a sample of the suspicious area to be looked at under a microscope. A biopsy is done when mammograms, other imaging tests, or the physical exam finds a breast change (or abnormality) that is possibly cancer. A biopsy is the only way to tell if cancer is really present.
There are several types of biopsies, such as fine needle aspiration biopsy, core (large needle) biopsy, and surgical biopsy. Each has its pros and cons. The choice of which to use depends on your specific situation. Some of the factors your doctor will consider include how suspicious the lesion appears, how large it is, where in the breast it is located, how many lesions are present, other medical problems you may have, and your personal preferences. You might want to discuss the pros and cons of different biopsy types with your doctor.
Fine needle aspiration biopsy
In a fine needle aspiration (FNA) biopsy, the doctor uses a very thin, hollow needle attached to a syringe to withdraw (aspirate) a small amount of tissue from a suspicious area, which is then looked at under a microscope. The needle used for an FNA biopsy is thinner than the ones used for blood tests.
If the area to be biopsied can be felt, the needle can be guided into the area of the breast change while the doctor is feeling (palpating) it.
If the lump can’t be felt easily, the doctor might use ultrasound to watch the needle on a screen as it moves toward and into the mass.
A local anesthetic (numbing medicine) may or may not be used. Because such a thin needle is used for the biopsy, the process of getting the anesthetic may actually be more uncomfortable than the biopsy itself.
Once the needle is in place, fluid is drawn out. If the fluid is clear, the lump is probably a benign cyst. Bloody or cloudy fluid can mean either a benign cyst or, very rarely, a cancer. If the lump is solid, small tissue fragments are drawn out. A pathologist will look at the biopsy tissue or fluid under a microscope to determine if it is cancerous.
While an FNA biopsy is the easiest type of biopsy to have, it has some disadvantages. It can sometimes miss a cancer if the needle is not placed among the cancer cells. And even if cancer cells are found, it is usually not possible to determine if the cancer is invasive. In some cases there may not be enough cells to perform some of the other lab tests that are routinely done on breast cancer specimens. If the FNA biopsy does not provide a clear diagnosis, or your doctor is still suspicious, a second biopsy or a different type of biopsy should be done.
Core needle biopsy
A core biopsy uses a larger needle to sample breast changes felt by the doctor or pinpointed by ultrasound or mammogram. (When mammograms taken from different angles are used to pinpoint the biopsy site, this is known as a stereotactic core needle biopsy.) In some centers, the biopsy can be guided by an MRI scan.
The needle used in core biopsies is larger than that used in FNA. It removes a small cylinder (core) of tissue (about 1/16- to 1/8-inch in diameter and ½-inch long) from a breast abnormality. Several cores are often removed. The biopsy is done using local anesthesia (where you are awake but the area is numbed) in an outpatient setting.
Because it removes larger pieces of tissue, a core needle biopsy is more likely than an FNAB to provide a clear diagnosis, although it may still miss some cancers.
Vacuum-assisted biopsies can be done with systems such as the Bard or Mammotome®. For these procedures the skin is numbed and a small incision (about ¼ inch) is made. A hollow probe is inserted through the incision into the abnormal area of breast tissue. The probe can be guided into place using x-rays or ultrasound (or MRI in the case of the ATEC system). A cylinder of tissue is then suctioned in through a hole in the side the probe, and a rotating knife within the probe cuts the tissue sample from the rest of the breast. Several samples can be taken from the same incision. Vacuum-assisted biopsies are done as an outpatient procedure. No stitches are needed, and there is minimal scarring. This method usually removes more tissue than core biopsies.
Surgical (open) biopsy
Sometimes, surgery is needed to remove all or part of the lump for microscopic examination. This is referred to as a surgical biopsy or an open biopsy. Usually this is an excisional biopsy, where the surgeon removes the entire mass or abnormal area, as well as a surrounding margin of normal-appearing breast tissue. If the mass is too large to be removed easily, an incisional biopsy may be done instead. In this type of biopsy only part of the mass is removed. In rare cases, this type of biopsy can be done in the doctor’s office, but it is more commonly done in the hospital’s outpatient department under a local anesthesia (where you are awake, but your breast is numbed). You may also be given medicine to make you drowsy. This type of biopsy can also be done under general anesthesia, (you are asleep).
During a surgical breast biopsy the surgeon may use a procedure called stereotactic wire localization if there is a small lump that is hard to locate by touch or if an area looks suspicious on the x-ray but cannot be felt. After the area is numbed with local anesthetic, a thin hollow needle is placed into the breast, and x-ray views are used to guide the needle to the suspicious area. Once the tip of the needle is in the right spot, a thin wire is inserted through the center of the needle. A small hook at the end of the wire keeps it in place. The hollow needle is then removed. The surgeon can then use the wire as a guide to the abnormal area to be removed. The surgical specimen is sent to the lab to be looked at under a microscope (see below).
This type of biopsy is more involved than an FNA biopsy or a core needle biopsy, typically requires several stitches and may leave a scar. Core needle biopsy is usually enough to make a diagnosis, but sometimes an open biopsy may be needed depending on where the lesion is, or if a core biopsy is not conclusive.
Lymph node dissection and sentinel lymph node biopsy
These procedures are done specifically to look for cancer in the lymph nodes. They are described in more detail in the section, “How is breast cancer treated?”
Laboratory examination of breast cancer tissue
The biopsy samples of breast tissue are looked at in the lab to determine whether breast cancer is present and if so, what type it is. Other lab tests can help determine how quickly a cancer is likely to grow and (to some extent) what treatments are likely to be effective.
If a benign condition is diagnosed, you will need no further treatment. Still, it is important to find out from your doctor if the benign condition places you at higher risk for breast cancer in the future and what type of follow-up you might need.
If the diagnosis is cancer, there should be time for you to learn about the disease and to discuss treatment options with your cancer care team, friends, and family. It is usually not necessary to rush into treatment. You may want to get a second opinion before deciding on what treatment is best for you.
Type of breast cancer
The tissue removed during the biopsy (or during surgery) is first looked at under a microscope to see if cancer is present and whether it is in situ (not invasive) or invasive. The biopsy is also used to determine the cancer’s type. The different types of breast cancer are defined in the section, “What is breast cancer?”
The most common types, invasive ductal and invasive lobular cancer, generally are treated in the same way.
Breast cancer grade
A pathologist also assigns a grade to the cancer, which is based on how closely the biopsy sample resembles normal breast tissue. The grade helps predict a woman’s prognosis. In general, a lower grade number indicates a slower-growing cancer that is less likely to spread, while a higher number indicates a faster-growing cancer that is more likely to spread. The tumor grade is one factor in deciding the need for further treatment after surgery.
Histologic tumor grade (sometimes called the Bloom-Richardson grade, Scarff-Bloom-Richardson grade, or Elston-Ellis grade) is based on the arrangement of the cells in relation to each other: whether they form tubules; how closely they resemble normal breast cells (nuclear grade); and how many of the cancer cells are in the process of dividing (mitotic count). This system of grading is used for invasive cancers but not for in situ cancers.
* Grade 1 (well differentiated) cancers have relatively normal-looking cells that do not appear to be growing rapidly and are arranged in small tubules.
* Grade 2 (moderately differentiated) cancers have features between grades 1 and 3.
* Grade 3 (poorly differentiated) cancers, the highest grade, lack normal features and tend to grow and spread more aggressively.
Ductal carcinoma in situ (DCIS) is sometimes given a nuclear grade, which describes how abnormal the cancer cells appear. The presence or absence of necrosis (areas of dead or degenerating cancer cells), which might indicate a more aggressive cancer, is also noted. Other factors important in determining the prognosis for DCIS include the surgical margin (how close the cancer is to the edge of the specimen) and the size (amount of breast tissue affected by DCIS). In situ cancers with high nuclear grade, necrosis, cancer at or near the edge of the sample, or large areas of DCIS are more likely to come back after treatment.
Estrogen receptor (ER) and progesterone receptor (PR) status
Receptors are proteins on the outside surfaces of cells that can attach to certain substances, such as hormones, that circulate in the blood. Normal breast cells and some breast cancer cells have receptors that attach to estrogen and progesterone. These 2 hormones often fuel the growth of breast cancer cells.
An important step in evaluating a breast cancer is to test a portion of the cancer removed during the biopsy (or surgery) to see if they have estrogen and progesterone receptors. Cancer cells may contain neither, one, or both of these receptors. Breast cancers that contain estrogen receptors are often referred to as ER-positive cancers, while those containing progesterone receptors are called PR-positive cancers. Women with hormone receptor–positive cancers tend to have a better prognosis and are much more likely to respond to hormone therapy than women with cancers without these receptors.
All breast cancers, with the exception of lobular carcinoma in situ (LCIS), should be tested for these hormone receptors when they have the breast biopsy or surgery. About 2 of 3 breast cancers contain at least one of these receptors. This percentage is higher in older women than in younger ones.
About 1 of 5 breast cancers have too much of a growth-promoting protein called HER2/neu (often just shortened to HER2). The HER2/neu gene instructs the cells to make this protein. Tumors with increased levels of HER2/neu are referred to as HER2-positive.
Women with HER2-positive breast cancers have too many copies of the HER2/neu gene, resulting in greater than normal amounts of the HER2/neu protein. These cancers tend to grow and spread more aggressively than other breast cancers.
All newly diagnosed breast cancers should be tested for HER2/neu because HER2-positive cancers are much more likely to benefit from treatment with drugs that target the HER2/neu protein, such as trastuzumab (Herceptin®) and lapatinib (Tykerb®). See the section, “How is breast cancer treated?” for more information on these drugs.
Testing of the biopsy or surgery sample is usually done in one of two ways:
* immunohistochemistry (IHC): In this test, special antibodies that identify the HER2/neu protein are applied to the sample, which cause cells to change color if many copies are present. This color change can be seen under a microscope. The test results are reported as 0, 1+, 2+, or 3+.
* fluorescent in situ hybridization (FISH): This test uses fluorescent pieces of DNA that specifically stick to copies of the HER2/neu gene in cells, which can then be counted under a special microscope.
Many breast cancer specialists feel the FISH test is more accurate than IHC. However, it is more expensive and takes longer to get the results. Often the IHC test is used first. If the results are 1+ (or 0), the cancer is considered HER2-negative. People with HER2-negative tumors are not treated with drugs (like trastuzumab) that target HER2. If the test comes back 3+, the cancer is HER2-positive. Patients with HER2-positive tumors may be treated with drugs like trastuzumab. When the result is 2+, the HER2 status of the tumor is not clear. This often leads to testing the tumor with FISH. Newer test methods are now becoming available as well (see “What’s new in breast cancer research and treatment?”).
Tests of ploidy and cell proliferation rate
The ploidy of cancer cells refers to the amount of DNA they contain. If there’s a normal amount of DNA in the cells, they are said to be diploid. If the amount is abnormal, then the cells are described as aneuploid. Although tests of ploidy may help determine prognosis, they rarely change treatment and are considered optional. They are not usually recommended as part of a routine breast cancer work-up.
The S-phase fraction is the percentage of cells in a sample that are replicating (copying) their DNA. DNA replication means that the cell is getting ready to divide into 2 new cells. The rate of cancer cell division can also be estimated by a Ki-67 test. If the S-phase fraction or Ki-67 labeling index is high, it means that the cancer cells are dividing more rapidly, which indicates a more aggressive cancer.
Tests of gene patterns
Researchers have found that looking at the patterns of a number of different genes at the same time (sometimes referred to as gene expression profiling) can help predict whether or not an early stage breast cancer is likely to come back after initial treatment. Two such tests, which look at different sets of genes, are now available.
Oncotype DX®: The Oncotype DX test may be helpful when deciding whether additional (adjuvant) treatment with chemotherapy (after surgery) might be useful in women with certain early-stage breast cancers that usually have a low chance of coming back (stage I or II estrogen receptor–positive breast cancers without lymph node involvement). Recent data has shown it may also be helpful for patients with positive lymph nodes.
The test looks at a set of 21 genes in cells from tumor samples to determine a ‘recurrence score’, which is a number between 0 and 100:
* Women with a recurrence score of 17 or below have a low risk of recurrence (coming back after treatment).
* Those with a score of 18 to 30 are at intermediate risk.
* Women with a score of 31 or more are at high risk.
The test estimates risk, but it cannot tell for certain if any particular woman will have a recurrence. It is a tool that can be used, along with other factors, to help guide women and their doctors when deciding whether more treatment might be useful.
MammaPrint®: This test can be used to help determine how likely certain early-stage (stage I or II) breast cancers are to recur in a distant part of the body after initial treatment. It can be used for either ER-negative or ER-positive tumors.
The test looks at the activity of 70 different genes to determine if the cancer is ‘low risk’ or ‘high risk’. This may help doctors decide if further (adjuvant) treatment might be needed.
To do a MammaPrint test, the tumor must be collected and stored in a certain way, so the decision to do this test must be made before surgery.
Usefulness of these tests: While some doctors are using these tests (along with other information) to help make decisions about offering chemotherapy, others are waiting for more research to prove they are helpful. Large clinical trials of these tests are now being done. In the meantime, women may want to discuss with their doctors whether or not these tests might be useful for them.