MEDICAL BLOGS:LUNG CANCER (Part 2)

Tests Conducted For Investigation And Staging Of Non Small Cell Lung Cancer( NSCLC)
            
                       

Imaging tests

·      To look at suspicious areas that might be cancer

·      To learn how far cancer may have spread

·      To help determine if treatment is working

·      To look for possible signs of cancer coming back after treatment 
Chest x-ray
A CT scan uses x-rays to make detailed cross-sectional images of your body. Instead of taking one picture, like a regular x-ray, a CT scanner takes many pictures as it rotates around you while you lie on a table. A computer then combines these pictures into images of slices of the part of your body being studied.
                               

Like CT scans, MRI scans provide detailed images of soft tissues. But MRI scans use radio waves and strong magnets instead of x-rays. A contrast material called gadolinium is often injected into a vein before the scan to better see details.
For this test, a form of radioactive sugar (known as FDG) is injected into the blood. Because cancer cells in the body are growing quickly, they absorb more of the radioactive sugar. This radioactivity can be seen with a special camera.
For this test, a small amount of low-level radioactive material is injected into the blood. The substance settles in areas of bone changes throughout the entire skeleton. This radioactivity can be seen with a special camera.
The actual diagnosis of lung cancer is made by looking at Lung Cells or Secretions under microscope:
A sample of mucus you cough up from the lungs (sputum) is looked at under a microscope to see if it has cancer cells.
If there is a buildup of fluid around the lungs (called a pleural effusion), doctors can perform thoracentesis to find out if it is caused by cancer spreading to the lining of the lungs (pleura).
An advantage of needle biopsies is that they don’t require a surgical incision.
Bronchoscopy
If lung cancer has been found, it’s often important to know if it has spread to the lymph nodes in the space between the lungs (mediastinum) or other nearby areas. This can affect a person’s treatment options.
Ultrasound is a type of imaging test that uses sound waves to create pictures of the inside of your body. For this test, a small, microphone-like instrument called a transducer gives off sound waves and picks up the echoes as they bounce off body tissues. The echoes are converted by a computer into an image on a computer screen.
This test is like endobronchial ultrasound, except the doctor passes an endoscope (a lighted, flexible scope) down the throat and into the esophagus (the tube connecting the throat to the stomach). This is done with numbing medicine (local anesthesia) and light sedation.
These procedures may be done to look more directly at and get samples from the structures in the mediastinum (the area between the lungs). They are done in an operating room by a surgeon while you are under general anesthesia (in a deep sleep). The main difference between the two is in the location and size of the incision.
Thoracoscopy can be done to find out if cancer has spread to the spaces between the lungs and the chest wall, or to the linings of these spaces.
For this test, very thin slices of the samples are attached to glass microscope slides. The samples are then treated with special proteins (antibodies) that attach only to a specific substance found in certain cancer cells.
In some cases, doctors may look for specific gene changes in the cancer cells that could mean certain targeted drugs help treat the cancer. For example:
Blood tests are not used to diagnose lung cancer, but they can help to get a sense of a person’s overall health and fitness for surgery.
Pulmonary function tests (PFTs) are often done after lung cancer is diagnosed to see how well your lungs are working

·      This is often the first test your doctor will do to look for any abnormal areas in the lungs.

Computed tomography (CT) scan

·      A CT scan is more likely to show lung tumors than routine chest x-rays.

·      It can also show the size, shape, and position of any lung tumors and can help find enlarged lymph nodes that might contain cancer that has spread from the lung.

·      This test can also be used to look for masses in the adrenal glands, liver, brain, and other internal organs that might be due to the spread of lung cancer.

CT-guided needle biopsy: If a suspected area of cancer is deep within your body, a CT scan can be used to guide a biopsy needle into the suspected area.

Magnetic resonance imaging (MRI) scan

·      MRI scans are most often used to look for possible spread of lung cancer to the brain or spinal cord.

·      Rarely, MRI of the chest may be done to see if the cancer has grown into central structures in the chest.

Positron emission tomography (PET) scan

PET/CT scan: Often a PET scan is combined with a CT scan using a special machine that can do both at the same time. This lets the doctor compare areas of higher radioactivity on the PET scan with the more detailed appearance of that area on the CT scan. This is the type of PET scan most often used in patients with lung cancer.

·      If you appear to have early stage lung cancer, your doctor can use this test to help see if the cancer has spread to nearby lymph nodes or other areas, which can help determine if surgery may be an option for you.

·      This test can also be helpful in getting a better idea if an abnormal area on another imaging test might be cancer.

·      PET/CT scans can also be useful if your doctor thinks the cancer might have spread but doesn’t know where. They can show spread of cancer to the liver, bones, adrenal glands, or some other organs.

·      They are not as useful for looking at the brain, since all brain cells use a lot of glucose.

·      PET/CT scans are often helpful in diagnosing lung cancer, but their role in checking whether treatment is working is unproven.

·      Most doctors do not recommend PET/CT scans for routine follow up of patients with lung cancer after treatment.

Bone scan

·      A bone scan can help show if a cancer has spread to the bones.

·      But this test isn’t needed very often because PET scans, which are often done in patients with non-small cell lung cancer, can usually show if cancer has spread to the bones.

·      Bone scans are done mainly when there is reason to think the cancer may have spread to the bones (because of symptoms such as bone pain) and other test results aren’t clear.

Test for diagnosis of Lung Cancer

Sputum cytology

·      The best way to do this is to get early morning samples for 3 days in a row. This test is more likely to help find cancers that start in the major airways of the lung, such as squamous cell lung cancers.

·      It may not be as helpful for finding other types of non-small cell lung cancer.

Thoracentesis 

·      For this procedure, the skin is numbed and a hollow needle is inserted between the ribs to drain the fluid.

·      If a malignant pleural effusion has been diagnosed, thoracentesis may be repeated to remove more fluid.

Fine needle aspiration (FNA) biopsy, the doctor uses a syringe with a very thin, hollow needle to withdraw (aspirate) cells and small fragments of tissue.

In a core biopsy, a larger needle is used to remove one or more small cores of tissue. Samples from core biopsies are larger than FNA biopsies, so they are often preferred. 

The drawback is that they remove only a small amount of tissue.

In some cases (particularly with FNA biopsies), the amount removed might not be enough to both make a diagnosis and to classify DNA changes in the cancer cells that can help doctors choose anticancer drugs.

Transthoracic needle biopsy: If the suspected tumor is in the outer part of the lungs, the biopsy needle can be inserted through the skin on the chest wall. The area where the needle is to be inserted may be numbed with local anesthesia first. The doctor then guides the needle into the area while looking at the lungs with either fluoroscopy (which is like an x-ray, but creates a moving image on a screen rather than a single picture on film) or CT scans.

If CT is used, the needle is inserted toward the mass (tumor), a CT image is taken, and the direction of the needle is guided based on the image. This is repeated a few times until the needle is within the mass.

Other approaches to needle biopsies: An FNA biopsy may also be done to check for cancer in the lymph nodes between the lungs:

·      Transtracheal FNA or transbronchial FNA is done by passing the needle through the wall of the trachea (windpipe) or bronchi (the large airways leading into the lungs) during bronchoscopy or endobronchial ultrasound 

·      In some patients an FNA biopsy is done during endoscopic esophageal ultrasound by passing the needle through the wall of the esophagus. 

·      Bronchoscopy can help the doctor find some tumors or blockages in the larger airways of the lungs, which can often be biopsied during the procedure.

For this exam, a lighted, flexible fiber-optic tube (called a bronchoscope) is passed through the mouth or nose and down into the windpipe and bronchi. The mouth and throat are sprayed first with a numbing medicine. You may also be given medicine through an intravenous (IV) line to make you feel relaxed.

Small instruments can be passed down the bronchoscope to take biopsy samples. The doctor can also sample cells from the lining of the airways with a small brush (bronchial brushing) or by rinsing the airways with sterile saltwater (bronchial washing). These tissue and cell samples are then looked at under a microscope.

Tests to find lung cancer spread in the chest:

Several types of tests can be used to look for this cancer spread.

Endobronchial ultrasound

·      For endobronchial ultrasound, a bronchoscope is fitted with an ultrasound transducer at its tip and is passed down into the windpipe. This is done with numbing medicine (local anesthesia) and light sedation.

·      The transducer can be pointed in different directions to look at lymph nodes and other structures in the mediastinum (the area between the lungs).

·      If suspicious areas such as enlarged lymph nodes are seen on the ultrasound, a hollow needle can be passed through the bronchoscope and guided into these areas to obtain a biopsy.

The samples are then sent to a lab to be looked at under a microscope.

Endoscopic esophageal ultrasound

The esophagus is just behind the windpipe and is close to some lymph nodes inside the chest to which lung cancer may spread.

As with endobronchial ultrasound, the transducer can be pointed in different directions to look at lymph nodes and other structures inside the chest that might contain lung cancer. If enlarged lymph nodes are seen on the ultrasound, a hollow needle can be passed through the endoscope to get biopsy samples of them.

The samples are then sent to a lab to be looked at under a microscope.

Mediastinoscopy and mediastinotomy

·      Mediastinoscopy: A small cut is made in the front of the neck and a thin, hollow, lighted tube is inserted behind the sternum (breast bone) and in front of the windpipe to look at the area. Instruments can be passed through this tube to take tissue samples from the lymph nodes along the windpipe and the major bronchial tube areas. Looking at the samples under a microscope can show if they have cancer cells.

·      Mediastinotomy: The surgeon makes a slightly larger incision (usually about 2 inches long) between the left second and third ribs next to the breast bone. This lets the surgeon reach some lymph nodes that can’t be reached by mediastinoscopy.

Thoracoscopy

·      It can also be used to sample tumors on the outer parts of the lungs as well as nearby lymph nodes and fluid, and to assess whether a tumor is growing into nearby tissues or organs.

·      This procedure is not often done just to diagnose lung cancer, unless other tests such as needle biopsies are unable to get enough samples for the diagnosis.

·      Thoracoscopy is done in the operating room while you are under general anesthesia (in a deep sleep). A small cut (incision) is made in the side of the chest wall. (Sometimes more than one cut is made.)

·      The doctor then puts a thin, lighted tube with a small video camera on the end through the incision to view the space between the lungs and the chest wall.

·      Using this, the doctor can see possible cancer deposits on the lining of the lung or chest wall and remove small pieces of tissue for examination. (When certain areas can’t be reached with thoracoscopy, the surgeon may need to make a larger incision in the chest wall, known as a thoracotomy.)

·      Thoracoscopy can also be used as part of the treatment to remove part of a lung in some early-stage lung cancers. This type of operation, known as video-assisted thoracic surgery (VATS).

Lab tests of biopsy and other samples

Samples that have been collected during biopsies or other tests are sent to a pathology lab.The results of these tests are described in a pathology report, which is usually available within about a week.

Immunohistochemical tests 

·      If the cancer cells have that substance, the antibody will attach to the cells.

·      Chemicals are then added so that antibodies change color.

·      The doctor who looks at the sample under a microscope can see this color change.

Molecular tests

·      The epidermal growth factor receptor (EGFR) is a protein that sometimes appears in high amounts on the surface of cancer cells and helps them grow. Some drugs that target EGFR seem to work best against lung cancers with certain changes in the EGFR gene, which are more common in certain groups, such as non-smokers, women, and Asians. 

·      But these drugs don’t seem to be as helpful in patients whose cancer cells have changes in the KRAS gene. 

·      Many doctors now test for changes in genes such as EGFR and KRAS to determine if these newer treatments are likely to be helpful. 

·      About 5% of non-small cell lung cancers (NSCLCs) have a change in a gene called ALK. This change is most often seen in non-smokers (or light smokers) who have the adenocarcinoma sub type of NSCLC. Doctors may test cancers for changes in the ALK gene to see if drugs that target this change may help them.

Blood tests

·      A complete blood count (CBC) looks at whether your blood has normal numbers of different types of blood cells. It also indicates if you are anemic

·      Blood chemistry tests can help spot abnormalities in some of your organs, such as the liver or kidneys.

Pulmonary function tests

·      This is especially important if surgery might be an option in treating the cancer.

Surgery to remove lung cancer may mean removing part or all of a lung, so it’s important to know how well the lungs are working beforehand.

Some people with poor lung function (like those with lung damage from smoking) don’t have enough lung reserve to withstand removing even part of a lung. These tests can give the surgeon an idea of whether surgery is a good option, and if so, how much lung can safely be removed.

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Author- 

   

Dr. Ganjoo 

Head-Yoddhas Medical Expert Panel