How is Lung Cancer Diagnosed?

Diagnosing lung cancer is an entirely systematic way in which the doctor takes an individual’s chief complaint, which caused him to visit a doctor, then history of present illness, then past medical history, social history, habits, smoking history, exposure to environmental and occupational substances and family history of cancer, physical examination, investigation and data diagnostics, which includes screening laboratory tests, chest x-ray, ultrasound, sputum test, fiberoptic bronchoscopy and percutaneous needle biopsy.

Patient's History

If the doctor suspects lung cancer, they will

  • Investigate your medical history
  • Perform a thorough physical examination
  • Order further specialised medical tests

Questions that are asked as part of your medical history, your doctor will ask about:

  • If you smoke or have smoked previously.
  • Your occupation and place of work.
  • If you have been exposed to occupational hazardous substances or radiation.
  • Whether you have a family history of lung cancer.

Diagnosing lung cancer


There are a series of screening tests that are done to look for signs of cancer before a person shows any symptoms. The purpose of screening is to enable the healthcare providers to detect lung cancer at very early stages when it is treatable. If the abnormal tissue or cancer is detected early enough then the chances of curing it are much higher rather than the symptoms appear when the tumor has spread to other organ structures of the body. There are several ways of diagnosing if someone is in the early stages of lung cancer.

Physical examination and history taking

Physical examination is performed to look whether the different organ systems are performing their function right or are there any abnormal signs that lead to the presence of any illness. The physical examination will include the examination from head to toe in which the organ systems, which will include will be, Head, eyes, ears, nose and throat (HEENT), respiratory system, cardiovascular system, gastrointestinal system, Endocrine system, Reproductive system, Integumentary system, Genital examination and Neurologic examination.

Laboratory tests

The laboratory tests will include a comprehensive list of lab tests that would include blood tests, urinalysis, comprehensive metabolic profile, and other tests, which the health care providers deem necessary to rule out the lung cancer and also to assist them in the planning, management and monitoring of the disease.

A sputum test is important, as it can help to look for the presence of cancer cells present in the lungs. The sputum is usually collected over a three-day period. Collecting the specimen over a three day period ensures a more accurate diagnosis than that made with a single sputum collection.

Fiberoptic bronchoscopy is a device, which is made up of small flexible rubber tube that passes from the nasal canal and then makes its way into the appropriate bronchus (airway), as it is being propelled down by the specialist and visualizes the place where the cancer is and can take samples from the tissues as the tube is making its way down the respiratory tract. The purpose of collecting the biopsy is to determine the exact type of lung cancer present so as to plan and administer the treatment according to it.

Percutaneous needle biopsy is another procedure in which the thin needle is inserted into the tumor through the skin of the chest wall. The purpose of this procedure is again to collect the specimen to look for the cancerous cells near the surface of the skin. This procedure is often done in conjunction with a CAT scan, which assists in guiding the needle into the tumor.

The excision or removal of a part of the suspected tumor can lead to further accurate diagnosis of the lung cancer. This test is performed by making a small incision into the chest, this clinical procedure involves using a small thin video camera, which is inserted into the chest to assist in removing a small block of lung tissue using a mechanical surgical stapling device or laser.

Mediastinoscopy is done to look into the mid portion of the chest through a small incision made just below the collar line. The purpose of doing this process is to take samples from the lymph nodes in the central part of the chest (mediastinum). The major function of this tumor is to determine as to how extensive the tumour is. If unfortunately the cancer has spread to the lymph nodes, the chance of surgically curing the lung cancer is automatically eliminated.

Mediastinotomy is a procedure done to remove samples of mediastinal lymph nodes. This is a complex test, and the patient has to undergo general anaesthesia. Unlike mediastinoscopy, in this procedure the surgeon has to open up the chest cavity by cutting through the sternum (breastbone) and/or the ribs. It allows the surgeon to reach and test more lymph nodes than he is able to reach through a mediastinoscopy.

Thoracentesis is a procedure performed by using a needle to remove a sample of fluid surrounding the lungs to check for cancer cells.

Thoracotomy is opening up of the chest cavity and can be useful if surgery is needed to test for malignancy. The chest wall has to be opened so this procedure is performed in hospital as a major operation.

Thoracoscopy is a procedure using a thin tube with lights, which is connected to a video camera to monitor and view the space between the lungs and the chest wall.

In a bone marrow biopsy a needle is used to remove a sample of bone about 1/16 inch across and 1 inch long (more often than not from the back of your hip bone). The sample is then checked under a microscope for cancer cells. This procedure is performed predominantly to diagnose small cell lung cancer.

Blood tests - A complete blood test is done to analyze whether the blood has the accurate number of different cell types by determining that the individual has anaemia or other related problems.
Testing of blood is repeated on a regular basis especially if someone is undergoing chemotherapy treatment. The blood-forming cells are affected by chemotherapy of the bone marrow and sometimes cause a lot of problematic side effects.

Blood chemistry tests spot abnormalities in organs and other parts of the body. If cancer has spread to the liver and bones, it might cause certain chemical abnormalities in the blood and exacerbate problems already suffered by the patient so it's important all eventualities are monitored for.
Other Tests and Procedures to Detect Lung Cancer Include:

Chest x-ray: About half of all x-rays obtained in the hospitals are chest x-rays. Chest x-rays are typically performed to gain an assessment of the lungs, heart and chest wall. A chest x-ray can identify pneumonia, heart enlargement, heart failure, emphysema, and other medical conditions as well as lung cancer.

It is the first test that doctors order to look for any tumour or spots on the lungs. If it is normal then there is a high probability that there is no lung cancer, but if anything suspicious is spotted, then the doctor will order further tests.

CT Scanning or Computed Tomography also known as CT or CAT Scan are used as unique equipment to obtain multiple cross-sectional images of organs and tissues of the body.
The CAT scans have an ability to produce images, which are far more detailed than a conventional chest x-ray and are especially useful for diagnosing cancers. The CAT scans also show many different types of body tissues including the lungs, heart, bones, soft tissues, muscle and blood vessels.

Now the modern CT scans employ a method called spiral (or helical) CT, which captures the images of the chest in many different angles. With the assistance of a computer, it processes the images to create cross-sectional pictures or "slices" from the area of concern.

It is also important to note that these images can then be printed out or examined on a monitor. In order to take a better picture after the first set is taken, an intravenous injection of a radio-contrast agent is administered. This radio-contrast agent helps to outline the structures within the body pretty well. After that, a second set of pictures is taken so they can be examined together.
The major help that CT scan provides is that it gives the precise information about the size, shape and position of a tumour, and helps discover any enlarged lymph nodes, which could contain cancer that has spread from the lung.

In general, CT scans are much more sensitive than an ordinary routine chest x-ray when looking for early lung cancers and it assists in ensuring that the patients receive treatment they need as soon as possible. A CT scan is also a very useful technique in tracing for tumors in the adrenal glands, brain and other internal organs, which occur because of the spread from the lung cancer.

Magnetic resonance imaging (MRI) scans use radio waves and strong magnets instead of x-rays. The energy that is released from the radio waves is absorbed and re-released in a pattern shaped by the type of tissue and the disease being investigated.

The high tech computers then translate the patterns of radio waves given by tissues and organs into very fine detailed images of parts of the body. Not only does this produce cross sectional slices of the body like a CT scanner, it can also produce slices parallel with the length of the body, which helps in enabling the surgeons and doctors to visualize the tumor from many different angles.

Positron Emission Tomography (PET) uses glucose, which is a form of sugar containing a radioactive atom. The cancer cells in the body then absorb large amounts of this radioactive sugar and a special camera is then able to detect the radioactivity.

A PET scan is a very useful test to discover an early stage lung cancer in any individual who is suffering from that and is often used to discover if the cancer has spread to the lymph nodes.
It's also valuable in ascertaining whether a shadow on a chest x-ray is cancer or not. PET scans are also helpful to determine the spread of the cancer when the doctors are not sure to the extent to which the cancer has spread to different organ systems. PET scans can also be used instead of several different x-rays because they scan your whole body.

Bone scans are performed with small amounts of radioactive substance (usually technetium diphosphonate), which is injected into a vein. The amount of radioactive substance used is very low and does not cause long-term effects. The radioactive substance is taken up in bone areas, which are suspected of having cancer metastasis.

It is of great importance to know that there are other bone conditions which might take up the radioactive dye, so it is really important to read those tests in conjunction with the results of other tests performed to rule out other disease to detect any false positive tests. Bone scans are usually performed on patients with small cell lung cancer. They are done specifically on them when other tests suggests that the cancer has spread to the bones.


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