How does cancer cause signs and symptoms?

Cancer is a group of diseases that can cause almost any sign or symptom. The signs and symptoms will depend on where the cancer is, how big it is, and how much it affects the organs or tissues. If a cancer has spread (metastasized), signs or symptoms may appear in different parts of the body. As a cancer grows, it can begin to push on nearby organs, blood vessels, and nerves. This pressure causes some of the signs and symptoms of cancer. If the cancer is in a critical area, such as certain parts of the brain, even the smallest tumor can cause symptoms. But sometimes cancer starts in places where it will not cause any signs or symptoms until it has grown quite large.

Cancers of the pancreas, for example, usually do not cause symptoms until they grow large enough to press on nearby nerves or organs (this causes back or belly pain). Others may grow around the bile duct and block the flow of bile. This causes the eyes and skin to look yellow (jaundice). By the time a pancreatic cancer causes signs or symptoms like these, it’s usually in an advanced stage. This means it has grown and spread beyond the place it started—the pancreas.

A cancer may also cause symptoms like fever, extreme tiredness (fatigue), or weight loss. This may be because cancer cells use up much of the body’s energy supply, or they may release substances that change the way the body makes energy from food. Or the cancer may cause the immune system to react in ways that produce these signs and symptoms. Sometimes, cancer cells release substances into the bloodstream that cause symptoms which are not usually linked to cancer. For example, some cancers of the pancreas can release substances that cause blood clots in veins of the legs. Some lung cancers make hormone-like substances that raise blood calcium levels. This affects nerves and muscles, making the person feel weak and dizzy.

How are signs and symptoms helpful?

Treatment works best when cancer is found early—while it’s still small and is less likely to have spread to other parts of the body. This often means a better chance for a cure,
especially if the cancer can be removed with surgery. A good example of the importance of finding cancer early is melanoma skin cancer. It can be easy to remove if it has not grown deep into the skin. The 5-year survival rate (percentage of people who live at least 5 years after diagnosis) at this stage is around 97%. Once melanoma has spread to other parts of the body, the 5-year survival rate drops below 20%. Sometimes people ignore symptoms. Maybe they don’t know that the symptoms could mean something is wrong. Or they might be frightened by what the symptoms could mean and don’t want to get or can’t afford to get medical help. Some symptoms, such as tiredness or coughing, are more likely caused by something other than cancer.

Symptoms can seem unimportant, especially if there’s an obvious cause or the problem only lasts a short time. In the same way, a person may reason that a symptom like a breast lump is probably a cyst that will go away by itself. But no symptom should be ignored or overlooked, especially if it has lasted a long time or is getting worse. Most likely, any symptoms you may have will not be caused by cancer, but it’s important to have them checked out, just in case. If cancer is not the cause, a doctor can help figure out what is and treat it, if needed. Sometimes, it’s possible to find cancer before you have symptoms.

The American Cancer Society and other health groups recommend cancer-related check-ups and certain tests for people even though they have no symptoms. This helps find certain cancers early, before symptoms start. For more information on early detection tests, see our document American Cancer Society Guidelines for the Early Detection of Cancer. But keep in mind, even if you have these recommended tests, it’s still important to see a doctor if you have any symptoms.

What are some general signs and symptoms of cancer?

You should know some of the general signs and symptoms of cancer. But remember, having any of these does not mean that you have cancer—many other things cause these signs and symptoms, too. If you have any of these symptoms and they last for a long time or get worse, please see a doctor to find out what’s going on.

Unexplained weight loss

Most people with cancer will lose weight at some point. When you lose weight for no known reason, it’s called an unexplained weight loss. An unexplained weight loss of 10 pounds or
more may be the first sign of cancer. This happens most often with cancers of the pancreas, stomach, esophagus (swallowing tube), or lung.

Fever

Fever is very common with cancer, but it more often happens after cancer has spread from where it started. Almost all patients with cancer will have fever at some time, especially if the
cancer or its treatment affects the immune system. (This can make it harder for the body to fight infection.) Less often, fever may be an early sign of cancer, such as blood cancers like
leukemia or lymphoma. Fatigue Fatigue is extreme tiredness that does not get better with rest. It may be an important symptom as cancer grows. It may happen early, though, in some cancers, like leukemia. Some colon or stomach cancers can cause blood loss that’s not obvious. This is another way cancer can cause fatigue.

Pain

Pain may be an early symptom with some cancers like bone cancers or testicular cancer. A headache that does not go away or get better with treatment may be a symptom of a brain tumor. Back pain can be a symptom of cancer of the colon, rectum, or ovary. Most often, pain due to cancer means it has already spread (metastasized) from where it started.

Signs and symptoms of certain cancers

Along with the general symptoms, you should watch for certain other common signs and symptoms that could suggest cancer. Again, there may be other causes for each of these, but
it’s important to see a doctor about them as soon as possible.

Change in bowel habits or bladder function

Long-term constipation, diarrhea, or a change in the size of the stool may be a sign of colon cancer. Pain when passing urine, blood in the urine, or a change in bladder function (such as
needing to pass urine more or less often than usual) could be related to bladder or prostate cancer. Report any changes in bladder or bowel function to a doctor.

Sores that do not heal

Skin cancers may bleed and look like sores that don’t heal. A long-lasting sore in the mouth could be an oral cancer. This should be dealt with right away, especially in people who smoke,
chew tobacco, or often drink alcohol. Sores on the penis or vagina may either be signs of infection or an early cancer, and should be seen by a health professional.

White patches inside the mouth or white spots on the tongue

White patches inside the mouth and white spots on the tongue may be leukoplakia. Leukoplakia is a pre-cancerous area that’s caused by frequent irritation. It’s often caused by smoking or other tobacco use. People who smoke pipes or use oral or spit tobacco are at high risk for leukoplakia. If it’s not treated, leukoplakia can become mouth cancer. Any longlasting mouth changes should be checked by a doctor or dentist right away.

Unusual bleeding or discharge

Unusual bleeding can happen in early or advanced cancer. Coughing up blood in the sputum (phlegm) may be a sign of lung cancer. Blood in the stool (which can look like very dark or black stool) could be a sign of colon or rectal cancer. Cancer of the cervix or the endometrium (lining of the uterus) can cause abnormal vaginal bleeding. Blood in the urine may be a sign
of bladder or kidney cancer. A bloody discharge from the nipple may be a sign of breast cancer

What are tumor markers?

Tumor markers are substances that can be found in the body when cancer is present. The classic tumor marker is a protein that can be found in the blood in higher than normal amounts when a
certain type of cancer is present, but not all tumor markers are like that. Some are found in urine or other body fluid, and others are found in tumors and other tissue. They may be made
by the cancer cells themselves, or by the body in response to cancer or other conditions. Most tumor markers are proteins, but some newer markers are genes or other substances.
There are many different tumor markers. Some are linked only to one type of cancer, while others can be found in many types of cancer. To test for a tumor marker, the doctor most often sends a sample of the patient’s blood or urine to a lab. Sometimes a piece of the tumor itself is tested for tumor markers.

Tumor markers alone are rarely enough to show that cancer is present. Most tumor markers can be made by normal cells as well as by cancer cells. Sometimes, noncancerous diseases can also cause levels of certain tumor markers to be higher than normal. And not every person with cancer may have higher levels of a tumor marker. This is why most doctors use only certain tumor markers. When a doctor looks at the level of a tumor marker, he or she will consider it along with the patient’s history, physical exam, and other lab tests or imaging tests. In recent years, doctors have begun to develop newer types of tumor markers. With advances in technology, levels of certain genetic materials (DNA or RNA) can now be measured. It’s been hard to identify single substances that provide useful information, but doctors are now beginning to look at patterns of genes or proteins in the blood. These new fields of genomics and proteomics are discussed in the section called “What’s new in tumor marker research?”

How are tumor markers used?

Tumor markers can be helpful in a number of ways.

Screening and early detection of cancer

Screening refers to looking for cancer in people who have no symptoms of the disease. Early detection is finding cancer at an early stage, when it’s less likely to have spread and is easier to treat. Tumor markers were first developed to screen for cancer – to look for cancer in people without symptoms – but very few markers have been shown to be helpful in this way.

A perfect tumor marker would be one that could be used as a cancer screening blood test for all people. The tumor marker would only be found in people with cancer. It would tell doctors the type of cancer, how much cancer there is, and which treatment would work best. At this time there are no tumor marker tests that work like this.

Today, the most widely used tumor marker is the prostate-specific antigen (PSA) blood test. The PSA test is used to screen men for prostate cancer. Men with prostate cancer usually have high PSA levels. But it’s not always clear what the test results mean — high PSA levels can be seen in men without cancer, and a normal PSA does not always mean that no cancer is present. PSA is not a perfect tumor marker. And at this time, not all doctors agree that PSA screening is right for all men. Right now, no other tumor marker is used to help screen for cancer in the general
population.

Some of the markers used now can help find cancer at an early stage, but they are only checked in people who are known to be at high risk for certain types of cancer.

Diagnosing cancer

Usually, tumor markers are not used to diagnose cancer. In most cases, cancer can only be diagnosed by a biopsy. (This means taking out some cells from a tumor so they can be checked for cancer by looking at the cells under a microscope.) Still, tumor markers can help figure out if cancer is a possibility. And if a cancer is already widespread when it’s found, tumor markers can help figure out where it started.

For instance, let’s say a woman has cancer throughout her pelvis and belly (abdomen). A high level of the tumor marker CA 125 will strongly suggest ovarian cancer, even if it isn’t clear after surgery that the cancer started in the ovary. This can be important because treatment can then be aimed at ovarian cancer. Alpha fetoprotein (AFP) is another example of a tumor marker that may be used to help diagnose cancer. The level of AFP can go up with some liver diseases, but when it reaches a certain high level in someone with a liver tumor, doctors can be fairly
sure that the tumor is liver cancer (a biopsy will still be needed, though). Advanced cancer Many tumor markers are helpful in checking people with advanced cancers. These tend to be cancers that are big (there’s a lot of cancer), have spread, and/or are affecting the way your body works. Advanced cancers are harder to treat and often have worse outcomes. In many cases, the tumor marker levels can be checked to see if treatment is working. (A series of levels over time should show a steady decrease when treatment is working.)

Determining the outlook (prognosis) for certain cancers

Some types of cancer grow and spread faster than others. But even within a cancer type, for instance testicular cancer, some cancers grow and spread more quickly or may be more or less responsive to certain treatments. Sometimes the level of a tumor marker can help predict the behaviour and outlook for certain cancers. In testicular cancer, very high levels of the tumor markers HCG (human chorionic gonadotropin) or AFP are a sign of a more aggressive cancer and a worse outlook for survival. Patients with these high levels may be given more aggressive cancer
treatments.

Seeing if certain treatments are likely to work

Certain markers found on cancer cells can be used to help predict if a certain treatment is likely to work. For example, in breast and stomach cancers, if the cells have too much of a protein called HER2, drugs such as trastuzumab (Herceptin®) can be helpful in treatment. If the cancer cells have normal amounts of HER2, the drugs won’t help. In cases like these, tumor tissue is checked for HER2 before treatment is started.

Seeing how well treatment is working

One of the most important uses for tumor markers is to watch patients being treated for cancer, especially advanced cancer. If a tumor marker is available for a certain type of cancer, the level of the marker may be able to be used to see if the treatment is working, instead of doing other tests like x-rays, CT scans, or bone scans. If levels of the tumor marker in the blood go down, it’s almost always a sign that the treatment is working. On the other hand, if the marker level goes up, then the cancer is not responding and the treatment may need to be changed. (One exception is if the cancer is very sensitive to certain chemotherapy treatment. In this case, the chemo can cause many cancer cells to die and release large amounts of the marker
into the blood, which will cause the level of the tumor marker to rise for a short time.)

Looking for recurrent cancer

Tumor markers are also used to look for cancer that might have come back (recurred) after treatment. Certain tumor markers may be useful once treatment is done and there is no sign of cancer in the body. For instance, people who have been treated for colorectal cancer often have their blood tested for levels of the tumor marker CEA. This tumor marker is often checked before any treatment (including surgery) is done. If it’s high, then it will be checked again during and after treatment. It should go down as treatment progresses, and be at a normal level after treatment. Then, the level may be checked as part of followup, and if it starts going up again, it may be a sign that the cancer has come back (recurred), even when the person has no symptoms. Often, when a patient’s CEA level goes up, their doctor will order imaging tests to see if a new tumor can be found early.

When are tumor markers checked?

Whether or not tumor markers are checked regularly depends on the type of cancer a person has. Tumor markers may be checked at diagnosis; before, during, and after treatment; and then regularly for many years to see if the cancer has come back. During treatment, changes in tumor marker levels can be a sign of whether treatment is working. Tumor marker levels can change over time. The changes are important, which is why results of a series of level tests often mean more than a single result. If at all possible it’s best to compare results from tests done at the same lab, and always be sure that the results are of the same value, such as ng/mL (nanograms per milliliter) or U/mL (units/milliliter).

The drawbacks of tumor markers

Early on in the search for tumor markers, the hope was that someday all cancers could be detected early with a blood test. A simple blood test that could find cancers in their earliest stages could prevent the deaths of millions of people. But very few tumor markers are useful for finding cancer at a very early stage. There are a few reasons for this:

• Almost everyone has a small amount of these markers in their blood, so it’s very hard to spot early cancers by using these tests.
• The levels of these markers tend to get higher than normal only when there’s a large amount of cancer present.
• Some people with cancer never have high tumor marker levels.
• Even when levels of these markers are high, it doesn’t always mean cancer is present. For example, the level of the tumor marker CA 125 can be high in women with gynaecologic conditions other than ovarian cancer.

These are the reasons why, today, tumor markers are used mainly in patients who have already been diagnosed with cancer to watch their response to treatment or look for the return of cancer after treatment.

Specific tumor markers

This section focuses on some of the tumor markers often used today. Tests for many other tumor markers are available through commercial testing labs, but these are seldom used. Some of these tests may even be advertised as being better than the more common markers, but this hasn’t yet been shown in scientific studies. In some of these cases, the tests have been taken off the market at the request of the Food and Drug Administration (FDA). Still, there are tests available for many types of cancer, but they have not yet been proven to work. There are also other tumor markers that are used by researchers. These are often not available to doctors or hospital labs. If research does show that they are useful, they are then made available to doctors and their patients. The tumor markers listed here are available to most doctors and have reliable scientific information showing that they are useful. The cancers described in these brief summaries are those for which the marker is usually tested.

These marker levels may be increased in other kinds of cancer, too. And though we list the other, less common cancer types that may affect certain tumor marker levels, in many cases it is not yet clear how helpful those tumor markers may be for those cancers. As with other kinds of lab tests, different labs may consider slightly different marker levels to be normal or abnormal. This can depend on a number of factors, including a person’s age and gender, which test kit the lab uses, and how the test is done. The values listed here are average values. Most labs will list their own “reference ranges” along with any test results you get. If you are tested for a tumor marker, be sure to ask the doctor what your test results mean.

Alpha-fetoprotein (AFP)

AFP can help diagnose and guide the treatment of liver cancer (hepatocellular carcinoma). Normal levels of AFP are usually less than 10 ng/mL (nanograms per milliliter). AFP levels are
increased in most patients with liver cancer. AFP is also elevated in acute and chronic hepatitis, but it seldom gets above 100 ng/mL in these diseases. In someone with a liver tumor, an AFP level over a certain value can mean that the person has liver cancer. In people without liver problems, that value is 400 ng/mL. But a person with chronic hepatitis often has high AFP levels. For them, AFP levels over 4,000 ng/mL are a sign of liver cancer.

AFP is also useful in following the response to treatment for liver cancer. If the cancer is completely removed with surgery, the AFP level should go down to normal. If the level goes
up again, it often means that the cancer has come back. AFP is also higher in certain germ cell tumors, such as some testicular cancers (those containing embryonal cell and endodermal sinus types), certain rare types of ovarian cancer (yolk sac tumor or mixed germ cell cancer), and germ cell tumors that start in the chest (mediastinal germ cell tumors). AFP is used to monitor the response to treatment, since high levels should go down when treatment works. If the cancer has gone away with treatment, the level should go back to normal. After that, any increase can be a sign that the cancer has come back.

Anaplastic lymphoma kinase (ALK)

Some lung cancers have changes in the ALK gene that cause the cancer cell to make a protein that leads to out of control growth. Tumor tissues can be tested for this gene change.
If it’s found, the patient can be treated with a drug that targets the abnormal protein, like crizotinib (Xalkori®).

BCR-ABL

Chronic myeloid leukemia (CML) cancer cells contain a new, abnormal gene called BCR-ABL. A test called PCR can find this gene in very small amounts in blood or bone marrow. In
someone with blood and bone marrow changes that look like those seen with CML, finding the gene confirms the diagnosis. Also, the level of the gene can be measured and used to
guide treatment.

Beta-2-microglobulin (B2M)

B2M blood levels are elevated in multiple myeloma, chronic lymphocytic leukemia (CLL), and some lymphomas (including Waldenstrom macroglobulinemia). Levels may also be higher in
some non-cancerous conditions, such as kidney disease and hepatitis. Normal levels are usually below 2.5 mg/L (milligrams per liter). B2M is useful in helping predict the long-term
outlook (prognosis) in some of these cancers. Patients with higher levels of B2M usually have poorer outcomes. B2M is also checked during treatment of multiple myeloma and Waldenstrom macroglobulinemia to see how well the treatment is working.

Bladder tumor antigen (BTA)

BTA is found in the urine of many patients with bladder cancer. It may be a sign of some non cancerous conditions, too, such as kidney stones or urinary tract infections. The results of the test are reported as either positive (BTA is present) or negative (BTA is not present). It’s sometimes used along with NMP22 (see below) to test patients for the return (recurrence) of bladder cancer.

This test is not used often. It’s not as good as cystoscopy (looking into the bladder through a thin, lighted tube) for finding bladder cancer, but it may be helpful in allowing cystoscopy to
be done less often during bladder cancer follow-up. At this time, most experts still consider cystoscopy the best way to diagnose and follow-up bladder cancer.

BRAF

Defects (mutations) in the BRAF gene can be found in melanoma, thyroid cancer, and colorectal cancer. About half of melanomas have a BRAF mutation, most often the one called BRAF V600.
This mutation causes the gene to make an altered BRAF protein that signals melanoma cells to grow and divide. This mutation can be tested for in tumor tissue. If it’s found, the patient
can be treated with a drug that targets the altered BRAF protein, such as vemurafenib (Zelboraf®).

CA 15-3

CA 15-3 is mainly used to watch patients with breast cancer. Elevated blood levels are found in less than 10% of patients with early disease and in about 70% of patients with advanced
disease. Levels usually drop if treatment is working, but they may go up in the first few weeks after treatment is started. (This rise is caused when dying cancer cells spill their contents into the bloodstream.) The normal level is usually less than 30 U/mL (units/milliliter), depending on the lab. But levels as high as 100 U/mL can be seen in women who do not have cancer. Levels of this marker can also be higher in other cancers, like lung, colon, pancreas, and ovarian, and in some non-cancerous conditions, like benign breast conditions, ovarian disease,
endometriosis, and hepatitis.

CA 19-9

The CA 19-9 test was first developed to detect colorectal cancer, but it’s most often used in people with pancreatic cancer. In very early disease the level is often normal, so it’s not
good as a screening test. Still, it’s the best tumor marker for following patients who have cancer of the pancreas. Normal blood levels of CA 19-9 are below 37 U/mL (units/milliliter). A high CA 19-9 level in a newly diagnosed patient usually means the disease is advanced. CA 19-9 can be used to watch bladder cancer and see how aggressive it is. It may also be used to watch colorectal cancer, but the CEA test is preferred for this type of cancer. CA 19-9 can be elevated in other forms of digestive tract cancer, especially cancers of the stomach and bile ducts, and in some non-cancerous conditions such as thyroid disease, rheumatoid arthritis, inflammatory bowel disease, and pancreatitis (inflammation of the pancreas).

CA 27-29

CA 27-29 is another marker that can be used to follow patients with breast cancer during or after treatment. This test measures the same marker as the CA 15-3 test, but in a different
way. Although it is a newer test than CA 15-3, it’s not any better in detecting either early or advanced disease. And it’s not elevated in all people with breast cancer. The normal level is usually less than 40 U/mL (units/milliliter), depending on the testing lab. This marker can be elevated in other cancers, too, such as cancers in the colon, stomach, kidney, lung, ovary, pancreas, uterus, and liver. It may also be higher than normal in some non-cancerous conditions, for instance, in women in the first trimester of pregnancy; and in people with endometriosis, ovarian cysts, non-cancerous breast disease, kidney stones, and liver disease.

CA 125

CA 125 is the standard tumor marker used to follow women during or after treatment for epithelial ovarian cancer (the most common type of ovarian cancer). Normal blood levels are usually less than 35 U/mL (units/milliliter). More than 90% of women with advanced ovarian cancer have high levels of CA 125. If the CA-125 level is increased at the time of diagnosis, changes in the CA-125 level can be used during treatment to get an idea of how well it’s working. Levels are also elevated in about half of women whose cancer has not spread outside of the ovary.

Because of this, CA 125 has been studied as a screening test. But the trouble with using it as a screening test is that it would still miss many early cancers, and problems other than
ovarian cancer can cause an elevated CA-125 level. For example, it’s often higher in women with uterine fibroids or endometriosis. It may also be higher in men and women with lung,
pancreatic, breast, liver, and colon cancer, and in people who have had cancer in the past. Because ovarian cancer is a rather rare disease, an increased CA-125 level is more likely to
be caused by something other than ovarian cancer.

Calcitonin

Calcitonin is a hormone produced by cells called parafollicular C cells in the thyroid gland. It normally helps regulate blood calcium levels. Normal calcitonin levels are below 5 to 12
pg/ml (picograms per milliliter). In medullary thyroid carcinoma (MTC), a rare cancer that starts in the parafollicular C cells, blood levels of this hormone are often greater than 100
pg/ml. This is one of the rare tumor markers that can be used to help detect early cancer. Because MTC is often inherited, blood calcitonin can be measured to detect the cancer in its very earliest stages in family members known to be at risk. Other cancers, like lung cancers and leukemias, can also elevate calcitonin levels, but calcitonin blood tests are not usually used for detecting these cancers.

Carcinoembryonic antigen (CEA)

CEA is not used to diagnose or screen for colorectal cancer, but it’s the preferred tumor marker to help predict outlook in patients with colorectal cancer. The normal range of blood levels varies from lab to lab, and smokers often have higher levels. But even in smokers, levels higher than 5.5 ng/mL (nanograms per milliliter) are not normal. The higher the CEA level at the time colorectal cancer is detected, the more likely it is that the cancer is advanced. CEA is also the standard marker used to follow patients with colorectal cancer during and after treatment. In this way CEA levels are used to see if the cancer is responding to treatment or if it has come back (recurred) after treatment. CEA may be used for lung and breast cancer. This marker can be high in some other cancers, too like melanoma, lymphoma, thyroid, pancreas, liver, stomach, kidney, prostate, ovary, cervix, and bladder cancer. If the CEA level is high at diagnosis, it can be used to follow the response to treatment. CEA can also be elevated in some non-cancerous diseases, like hepatitis, chronic obstructive pulmonary disease (COPD), colitis, rheumatoid arthritis, and pancreatitis, and in otherwise healthy smokers.

Chromogranin A

Chromogranin A (CgA) is made by neuroendocrine tumors, which include carcinoid tumors, neuroblastoma, and small cell lung cancer. The blood level of CgA is often elevated in people
with these diseases. It’s probably the most sensitive tumor marker for carcinoid tumors. It’s abnormal in 1 out of 3 people with localized disease and 2 out of 3 of those with cancer that has spread (metastatic cancer). Levels can also be elevated in some advanced forms of prostate cancer that have neuroendocrine features. It’s hard to define the normal level for CgA because
there are different ways to test for this marker and each has its own normal value. Taking drugs called proton-pump inhibitors (such as omeprazole and lansoprazole) to reduce
stomach acid can raise CgA levels in healthy people, so be sure your doctor know what drugs you are taking before this lab test is done.

Epidermal growth factor receptor (EGFR)

This protein, also known as HER1, is a receptor found on cells that helps them grow. Tests done on a piece of the cancer tissue can look for increased amounts of these receptors,
which is a sign that the cancer may grow fast, spread quickly, and be harder to treat. Patients with elevated EGFR may have poorer outcomes and need more aggressive treatment, particularly with drugs that block (or inhibit) the EGFR receptors. EGFR may be used to guide treatment and predict outcomes of non-small cell lung, head and neck, colon, pancreas, or breast cancers. The results are reported as a percentage based on the number of cells tested.

Some lung cancers have certain defects (mutations) in the EGFR gene that make it more likely that certain drugs will work against the cancer. These gene changes are more common in lung cancer patients who are women, non-smokers, or Asian.

HER2 (or HER2/neu, erbB-2, or EGFR2)

HER2 is a protein that tells some cancer cells to grow. It’s present in larger than normal amounts on the surface of breast cancer cells in about 1 out of 5 people with breast cancer.
Higher than normal levels can be found in some other cancers, too, such as some stomach and esophageal cancers. HER2 is usually found by testing a sample of the cancer tissue itself,
not the blood.

Cancers that are HER2-positive tend to grow and spread faster than other cancers. All newly diagnosed breast cancers and advanced stomach cancers should be tested for HER2.
HER2-positive cancers are more likely to respond to drugs that work against the HER2 receptor on cancer cells.

Hormone receptors

Breast tumor samples – not blood samples – from all people with breast cancer are tested for estrogen and progesterone receptors. These 2 hormones often fuel the growth of breast
cancer cells. Breast cancers that contain estrogen receptors are often called ER-positive; those with progesterone receptors are PR-positive. About 2 out of 3 breast cancers test
positive for at least one of these markers. Hormone receptor-positive breast cancers tend to grow more slowly and may have a better outlook than cancers without these receptors.
Cancers that have these receptors can be treated with hormone therapy such as tamoxifen or aromatase inhibitors.

Some gynecologic tumors, such as endometrial cancers and endometrial stromal sarcomas, are also checked for hormone receptors to see if they can be treated with hormone therapy
drugs.

Human chorionic gonadotropin (HCG)

HCG (also known as beta-HCG or β-HCG) blood levels are elevated in patients with some types of testicular and ovarian cancers (germ cell tumors) and in gestational trophoblastic
disease, mainly choriocarcinoma. They are also higher in some people with mediastinal germ cell tumors — cancers in the middle of the chest (the mediastinum) that start in the same
cells as germ cell tumors of the testicles and ovaries. Levels of HCG can be used to help diagnose these conditions and can be watched over time to see how well treatment is working. They can also be used to look for cancer that has come back after treatment has ended (recurrence).

An elevated blood level of HCG will also raise suspicions of cancer in certain situations. For example, in a woman who still has a large uterus after pregnancy has ended, a high blood
level of this marker might be a sign of a cancer. This is also true of men with an enlarged testicle or anyone with a tumor in their chest. It’s hard to define the HCG normal level because there are different ways to test for this marker and each has its own normal value.

Immunoglobulins

Immunoglobulins are not classic tumor markers but instead are antibodies, which are blood proteins normally made by immune system cells to help fight germs. There are many types
of immunoglobulins, including IgA, IgG, IgD, and IgM. Bone marrow cancers such as multiple myeloma and Waldenstrom macroglobulinemia often cause a person to have too much of
one type of immunoglobulin in the blood. These cancers can also cause pieces of immunoglobulin to be found in the urine. A high level of immunoglobulins may be a sign of
one of these diseases.

There are normally many different immunoglobulins in the blood, with each one differing very slightly from the others. A classic sign in patients with myeloma or macroglobulinemia
is a very high level of a certain monoclonal immunoglobulin. This can be seen on a test called serum protein electrophoresis (also called SPEP). In this test, the blood proteins are
separated by an electrical current. With myeloma or macroglobulinemia, the monoclonal immunoglobulin forms a monoclonal “spike” on the SPEP. This is often called the M spike,
monoclonal protein, or M protein. The level of the spike is important because some people may show low levels of a spike without having myeloma or macroglobulinemia. The
diagnosis of multiple myeloma or Waldenstrom macroglobulinemia must be confirmed by a biopsy of the bone marrow. Immunoglobulin levels can also be followed over time to help see how well treatment is working.

Prostate-specific antigen (PSA)

PSA is a tumor marker for prostate cancer. PSA is a protein made by cells of the prostate gland, which is found only in men. It’s the only marker used to screen for a common type of
cancer, but most medical groups do not recommend using it routinely to screen all men. (The American Cancer Society recommends that men talk to a doctor and make informed
decisions about testing.) The level of PSA in the blood can be elevated in prostate cancer, but PSA levels can be affected by other things, too. Men with benign prostatic hyperplasia (BPH), a non-cancerous growth of the prostate, often have higher levels. The PSA level also tends to be higher in older men and those with infected or inflamed prostates. It can also be elevated for a day or 2 after ejaculation.

PSA is measured in nanograms per milliliter (ng/mL). Most doctors feel that a blood PSA level below 4 ng/mL means cancer is unlikely. Levels higher than 10 ng/mL mean cancer is
likely. The area between 4 and 10 is a gray zone. Men with PSA levels in this borderline range have about a 1 in 4 chance of having prostate cancer. A doctor may recommend a
prostate biopsy (getting samples of prostate tissue to look for cancer) for a man with a PSA level above 4 ng/mL.

Not all doctors agree with these cutoff points. This is because some men with prostate cancer do not have an elevated PSA level, while some others with a borderline or elevated level will not have cancer.

Some doctors believe it’s more useful to follow the PSA level over time because an increase from one year to the next might mean prostate cancer is more likely. This is called PSA
velocity. Most doctors believe that PSA levels should be measured at least 3 times over a period of at least 18 months in order to get an accurate PSA velocity. Still, it’s not clear if
measuring PSA velocity is any more helpful than looking at PSA levels alone.

Doctors are also looking at the PSA level in other ways to see if it might be more useful. A helpful test when a PSA value is in the borderline range (between 4 and 10 ng/mL) is
measurement of the free PSA (also percent-free PSA or fPSA). PSA is in the blood in 2 forms— some is bound to a protein and some is free. The fPSA is the ratio of how much PSA
circulates free compared to the total PSA level. A lower fPSA means that the likelihood of having prostate cancer is higher and a biopsy should probably be done. Many doctors
recommend biopsies for men whose fPSA is 10% or less, and advise men to consider having a biopsy if it’s between 10% and 25%. Using these cutoffs detects most cancers and helps
some men avoid unnecessary prostate biopsies. This test is widely used, but not all doctors agree that 25% is the best cutoff point to decide on a biopsy, and the cutoff may change
depending on PSA level.

The PSA test is very valuable in monitoring the response to treatment and in the follow-up of men with prostate cancer. In men who have been treated with surgery meant to cure the
disease, the PSA should fall to an undetectable level. The PSA should also go down after treatment with radiation therapy (although it doesn’t go away completely). A rise in the PSA
level may be a sign the cancer is coming back.

S-100

S-100 is a protein found in most melanoma cells. Tissue samples of suspected melanomas may be tested for this marker to help in diagnosis. Some studies have shown that blood levels of S-100 are elevated in most patients with metastatic melanoma (melanoma that has spread to other parts of the body). So, this test is sometimes used to look for melanoma spread before, during, or after treatment.

Thyroglobulin

Thyroglobulin is a protein made by the thyroid gland. Normal blood levels depend on a person’s age and gender. Thyroglobulin levels are elevated in many thyroid diseases, including some common forms of thyroid cancer. Thyroglobulin levels in the blood should fall to undetectable levels after treatment for thyroid cancer. A rise in the thyroglobulin level after treatment can mean the cancer has come back (recurred). In people with thyroid cancer that has spread, thyroglobulin levels can be followed over time to watch the results of treatment.

Some people’s immune systems make antibodies against thyroglobulin, which can affect test results. Because of this, levels of anti-thyroglobulin antibodies are often measured at the same time.