How Lung Cancer Is Diagnosed

Excerpted from
Living With Lung Cancer
A Guide for Patients and Their Families

Lung cancer will usually be suspected in a smoker who has a change in respiratory symptoms, unexplained weight loss or bone pain. It is often discovered in the first few years after a person has quit smoking, perhaps because of a cough or other subtle change in symptoms.

Often lung cancers are picked up on a routine chest X-ray in a person experiencing no symptoms. If cancer cells start to grow in one of the bronchioles (the smallest branches of the breathing tree) near the aveoli (tiny air sacs), the tumor can become the size of a golf ball or even larger without causing symptoms. Even when the chest X-ray looks normal, cancer may be suspected if the person has coughed up blood, develops persistent hoarseness, has chest pain or difficulty in breathing, or has had repeated episodes of pneumonia in the same place in the lung.

Signs and symptoms
Sometimes small ulcers appear on a lung tumor and make it bleed. About half of lung cancer patients have blood or streaks of blood in their sputum. You may see streaks of blood in the mucus that you cough up. Heavy bleeding, however, is rare.

When a tumor on the lining of a breathing tube grows, it may block the free flow of air through the breathing tube, resulting in a wheeze or a whistling noise. A deep breath may cause chest pain or shoulder pain, shortness of breath, or noisy breathing. If the tumor damages one of the nerves that goes to the larynx (voice box), hoarseness may result.

Chest pain and difficulty in breathing may also result if the tumor spreads to the outside surface of the lung, causing fluid to collect in the pleural cavity, the space between the lung and ribs. If a tumor presses on the blood vessels that carry blood to and from the heart, the normal blood flow may be blocked.

A growing tumor may interfere with the normal movement of mucus up and out of the lungs, causing a cough or making an existing cough worse. When it blocks a main breathing tube, it can cause shortness of breath. It may also keep the mucus produced in the bronchial tubes from being swept upward (past the tumor) and out of the lungs, as it should. So the mucus backs up in the lung, causing a type of pneumonia.

Sometimes the first sign of lung cancer is pneumonia, with fever, chills, and chest pain. There may also be a cough with yellow sputum when the tumor blocks off a bronchial tube and infection develops behind the blockage. If a tumor spreads directly from the lung into the tissues of the chest wall, it may cause pain. It may grow from the lung toward the center of the chest, between the lungs, and press on the esophagus (swallowing tube). This pressure may make swallowing difficult until the tumor is found and treated.

Sometimes the first symptoms are in an area outside of the chest to which the cancer has spread. There may be headache or dizziness, bone pain, or lymph node enlargement. Persistent hoarseness may develop, as well as clubbing, a rounding and widening of the nails and fingertips.

Examination and diagnostic tests
Both your general health and your respiratory status will be evaluated. A detailed medical history will be taken. You will be asked about previous illness, smoking and occupational history, respiratory symptoms and general health. A complete physical examination will be done with special attention to the lungs, the lymph nodes in your neck and underarms, and the abdomen. If surgery is a possibilty, your doctor needs to determine whether you can tolerate surgery.

Many different kinds of tests may be used: several kinds of X-ray examinations, as well as other methods of obtaining a picture of the inside of the body. Your doctor will decide which ones you need. Instruments may be used to look into various parts of the body, and in some cases specimens will be taken for examination in the laboratory. Sputum, blood, urine and other body fluids will be examined. If necessary, an operation will be performed to complete the diagnosis.

Although some people believe that lung cancer can be diagnosed by a blood test, this is not true. Blood tests may help determine whether the cancer has spread to an organ such as the liver, but such tests must be done in conjunction with other studies.

You may be given one or more of the following tests.

Chest X-ray
Since lung cancer can usually be seen on the X-ray film, a chest X-ray is one of the first tests you will have. As with most types of X-ray pictures, a chest X-ray causes no discomfort.

The smallest tumor that can be seen on a chest X-ray is about 1/2-inch in diameter. But even if a tumor is not seen, the chest X-ray may offer other clues to the diagnosis, such as pneumonia in the lung. Other possible clues are enlarged lymph nodes (which may be filled with cancer cells), and pleural effusion, an accumulation of fluid in the space between the lung and the chest wall. Lung cancer is not always the cause of these, but they are signs that alert the doctor to look for the cause, using other diagnostic tools.

Your doctor may want you to have a chest X-ray even if the diagnosis is already clear. The purpose is to be able to compare it with previous and later X-rays, to follow your progress and watch for possible changes in the lung tissue. It is important for your doctor to find out whether the cancer is growing, or whether it is responding to treatment and shrinking.

CAT scan (also called CT scan)
Patients with suspected lung cancer will almost always have a CAT (computerized axial tomography) scan of the chest and upper abdomen to help in diagnosis and staging. Other areas such as the head or back may be scanned if worrisome symptoms are present.

A CAT scan is a type of X-ray study combined with computer processing to provide a much more detailed picture of the lymph nodes and blood vessels in your lungs and chest than an ordinary chest X-ray can. Your doctor will be able to make a more exact evaluation of the size and extent of the tumor, the presence of enlarged lymph nodes, and whether bones or vital structures and organs are involved.

To allow a better picture, dye will probably be injected into a vein in your arm. Be sure to inform your doctor if you have ever had an allergy to X-ray dye or to seafood. Aside from the needle stick for the dye, a CAT scan is painless. The X-ray machine will move around you and you will be asked to hold your breath for several seconds as pictures are taken.

MRI (magnetic resonance imaging)
With this technique, detailed pictures of various organs are obtained using a magnetic field. It is painless, but may involve lying in a confined space for up to 30 minutes. If you think that being in an enclosed space may make you uncomforable or anxious, ask about receiving a mild tranquilizer before the test. (Some newer MRI machines are more open.) The MRI is usually used for brain imaging when headache is one of the symptoms. It may also be used to evaluate blood vessel or bone involvement of a lung tumor, when this information is not clear on the CAT scan.

Sputum cytology
You may be asked for a sputum sample, so it can be examined under the microscope for the presence of cancer cells. In this way, the diagnosis of lung cancer and its specific cell type can sometimes be made without the need for more invasive testing. If you are unable to cough up a deep sputum sample, you may be given a mist of moisturized air to inhale, to stimulate sputum production.

Bronchoscopy
A flexible lighted tube called a fiberoptic bronchoscope is used to examine the airways, to see the tumor. The doctor needs to learn its type and exact location. This information is important for deciding whether surgery will be possible. If the tumor is not visible, an X-ray can help localize it so that the doctor can obtain biopsies through the bronchoscope.

Bronchoscopy is usually an outpatient procedure. You will be asked to arrive with an empty stomach and to bring a friend or relative who will be able to drive you home.

For the procedure, you will lie on a padded table equipped with an X-ray machine. A technician will connect you to heart, blood pressure and oxygen monitors. You will be given a local anesthetic as a mist, either to inhale or as a throat spray, and then sedated through a small IV in your hand or arm. Your nose will be numbed with an anesthetic gel, and then the scope will enter your nose and travel through the nose into your airway. Fluid is washed into your lung through the scope to allow cells to be collected for examination. Biopsies will most likely also be done.

There are no pain fibers in your lung, so the biopsies will not hurt. You will be closely monitored during the procedure and may spend a couple of hours in a recovery room. The main discomfort of bronchoscopy is from coughing, and your throat may be a little sore. If biopsies are done, you may cough up a small amount of blood.

Needle biopsy (fine needle aspiration biopsy)
Sometimes a tumor is located in a place that is easier to biopsy from the outside than through the bronchoscope. In that case a radiologist will perform the biopsy, using an X-ray or CAT scan to locate the tumor.

Your skin will be numbed with a local anesthetic, then a needle will be inserted through the skin between the ribs and into an area of disease in the lung. X-ray guidance ensures that the needle is inside the pulmonary lesion. Cells removed from the tumor will be examined under the microscope for evidence of cancer.

There is a small chance that air will escape from your lung causing some degree of lung collapse (pneumothorax). You will have a chest X-ray after the procedure and will be observed for an hour or two to assure that all is well. This is usually a minor problem and the lung re-expands without any special treatment. If the collapse is more complete, air will need to be removed from the pleural space by inserting a tube between the ribs and into the chest, and connecting the tube to a suction pump.

The biopsy report. All biopsies, whether taken through the bronchoscope or a needle, need to be processed and then read by a pathologist. This process may take 1 to 3 days. The wait will be difficult for you, but it is important. There is a possibility that your biopsy will come back "negative" (no cancer), even if there is cancer. The tumor may be in an area that is difficult to reach, for example. Your physician may recommend surgery to remove a suspicious nodule, even when the biopsy does not show cancer.

Pulmonary function studies
If surgery is a possible treatment, you must have enough lung capacity to allow part of your lung to be removed. Measuring lung capacity is especially important if you are (or were) a cigarette smoker because smoking is also a risk factor for emphysema, and if you have emphysema, your lung capacity might be diminished.

Lung capacity is determined by measuring the amount of gas you can blow out of your lung with maximum effort. This will be hard work, but do your best. You will likely have blood drawn from an artery in your wrist to measure oxygen and carbon dioxide levels in your blood, which also helps determine how well your lungs are working.

If your lung function is decreased, you may be asked to have a nuclear medicine lung scan to evaluate lung function in more detail. In this test, a tiny amount of radioactive material is placed in your vein and a machine scans over your lungs. The information gained helps the physician determine whether your right and left lungs share equally in your lung capacity and whether you will have sufficient lung capacity after part or all of one lung is removed. In some instances, exercise testing on a bicycle or treadmill may also be used to evaluate your lung capacity and your ability to tolerate surgery.

Thoracentesis
The chest X-ray may show fluid in the space between the lung and the chest wall -- a pleural effusion. There are many possible causes of such fluid; one cause is spread of cancer to the pleural space. If cancer cells are found, surgical cure is not possible. Therefore the fluid must be examined. This is done by means of a minor procedure called thoracentesis.

For the procedure, your chest wall (usually in the back) is cleaned and numbed with a local anesthetic. Then a needle is introduced between the ribs into the pleural space and fluid is gently withdrawn. Sometimes a slightly larger needle is used for a biopsy. The fluid and/or biopsy are examined for cancer cells. Thoracentesis can also provide relief of symptoms if you have a large amount of fluid that is causing shortness of breath or chest pain.

Thoracoscopy, Mediastinoscopy, Thoracotomy
These are surgical procedures that are performed under general anesthesia in the operating room.

Thoracoscopy -- named for the instrument used -- is usually used if you have a nodule (rounded abnormality) at the edge of the lung, and it has not been diagnosed as cancer by a previous biopsy. The surgeon makes three small chest incisions for inserting a scope and biopsy instruments. The nodule is removed and examined by the pathologist under the microscope. If cancer is found, the surgeon will remove the lobe with the nodule (thoracotomy), usually at the same time. For thoracoscopy alone, the hospital stay is about 2-3 days.

Mediastinoscopy -- frequently an outpatient procedure -- is named for the mediastinum, the area of the chest behind the breastbone. It is used in evaluating the lymph nodes in the center of the chest, to determine whether cancer has spread. The surgeon inserts a scope through a small curved incision at the base of the neck, at the top of the breastbone. Biopsies are taken through the scope. This procedure can establish a definite diagnosis when the X-ray or CAT scan has shown enlarged lymph nodes. It may also be done as a staging procedure when a curative operation is planned, to assure that the cancer has not spread to the central lymph nodes. (If cancer is found in these nodes, an operation to remove the lung tumor will usually be delayed until it is determined whether pre-operative treatment with chemotherapy and/or radiation therapy would be helpful.)

Thoracotomy may be done when the chest X-ray is suspicious for cancer, but cancer has not been definitely diagnosed. It is a way to biopsy the suspicious area. The surgeon makes an incision, several inches long, in your chest to allow removal of a tumor and the surrounding lung tissue. The tissue is examined by a pathologist. If cancer is diagnosed and is a type that can be effectively treated by surgery, the surgeon will perform the operation at that time. The diagnosis and treatment will be accomplished with the same operation.

Other procedures
Most of the remaining diagnostic procedures are for finding out whether the cancer has spread to any other organs. For example, if you have pain that feels as if it comes from bone, you may have a bone scan. Much like an X-ray, a bone scan is painless. A small amount of sterile, radioactive liquid is injected into a vein in your arm. The amount of radioactivity is small and is harmless to you. If there are any cancerous spots in the bone, they will absorb the radioactive liquid and show on the scan, indicating that the disease has probably spread to that bone. The doctor will then check for metastatic cancer with X-rays of those bones.

The liver is another place where lung cancer cells can start growing. A liver scan may be ordered if your liver feels abnormally large during the examination, or if certain blood tests indicate that it is not working properly.