Lungs – Diagnostic Tests for Lung Cancer

When a patient reports any of the symptoms of lung cancer, or something suspicious shows up on an x-ray, the next step is to obtain a definitive diagnosis. There are fortunately a wide-array of modern techniques to carry that out. An x-ray, for example, can display worrisome shadows, but other tests will show for sure whether or not a type of carcinoma exists.

X-rays can be supplemented with a CT scan. (CT stands for computer tomography, an imaging technique.) A PET scan (positron emission tomography) can provide a more extensive visual depiction of the area. A harmless radioactive isotope is injected to ‘light up’ certain areas, since tumor cells absorb the material differently than normal cells do. Radiologists can then examine the results.

But an actual sample of lung tissue remains one of the best methods of detecting tumors. It is obtained by a biopsy, which can be carried out in a number of ways.

Bronchoscopy is a common method for obtaining a sample. With the patient under anasthesia, a physician passes a flexible tube down the throat or through the nose. At the end of the tube are small ‘scissors’ that clip off a tiny piece of tissue. The sample is sent to a pathologist, who looks for characteristic tumor cells.

Another common method for obtaining a tissue sample is a technique called ‘fine needle aspiration’. A thin needle can be inserted into a lymph node near the lungs, which then sucks in a few sample cells. The fluid is given to a pathologist who once again looks for the signs of a tumor.

A more invasive technique may be required, such as mediastinoscopy. In this method, a small incision is made at the base of the throat. The physician guides a small tube through the slit and down into the lymph nodes in the chest.

Since one symptom of lung cancer is fluid in the lungs (a condition known as ‘pleural effusion’), extracting some of that fluid can give doctors clues. A technique called thoracentesis is used to obtain the fluid. A physician inserts a thin needle through the chest wall between the ribs. The liquid is then sucked up through the needle and examined for evidence of cancer cells.

There are supplemental data and tests that a physician will use in the diagnosis of lung cancer.

A medical history is important, since many choices (such as smoking) increase the odds of cancer. A family history is recorded, since genetic factors play a role. Pulmonary function tests, such as spirometry, help determine how efficiently the lungs are operating.

Lung cancer develops in about 1/4 of cases where patients show no symptoms at all in early stages. So, early detection is vital to provide the widest number of treatment options and the best possible chances of full recovery.

 

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