Lung Cancer Diagnosis
Diagnosis of lung cancer can be a daunting experience, due in part, to the latency of symptoms. To this effect, lung cancer and mesothelioma are quite similar, as patients of both were typically exposed to the causation decades prior to exhibiting any symptoms. As with any diagnosis a thorough medical evaluation performed by a licensed physician or specialist is necessary. The Mayo Clinic suggests that a proper evaluation includes a biopsy of lung tissue which is then examined under a microscope by a pathologist. This examination of body tissue allows the pathologist to better determine diagnosis and staging. It is not unusual for lung cancer to be diagnosed while seeking medical advice for other reasons. Again, this is mostly due to the time it takes lung cancer symptoms to present. Symptoms of mesothelioma, like lung cancer, often go undetected for long periods of time because they mimic other conditions. As mentioned, a biopsy is a critical element of cancer detection, requiring not only a collection of tissue but further examination of that tissue under a microscope. There are a variety of ways in which a doctor can collect these tissues which are explained in detail below:
- Bronchoscopy-This procedure utilizes a lighted, flexible tube known as a bronchoscope. After a numbing agent is applied the tube is passed down the windpipe with an attached ultrasound transducer. The transducer helps the doctor observe the interior of the lungs from multiple directions. The bronchoscope is structured in such a way that, should it be required, other instruments can be placed down the tubing to aid in collecting lung secretions and tissue samples.
- Fine-needle aspiration-A fine, hollow needle is inserted into tissues such as a lymph node or tumor in order to remove cells for review by a pathologist. This test is usually required when the sample needed is not located close enough to large airways. Often this procedure does not require a surgical incision, and rarely requires an overnight hospital stay.
- Sputum Cytology- Although not a biopsy in the traditional sense, this test requires a sample of phlegm which is then observed under a microscope.
- Endobronchial Ultrasound-Performed in much the same way as the bronchoscopy, this test also involves an ultrasound transducer being placed down the windpipe with the availability to place a hollow needle inside the tube should the doctor decide a tissue sample is needed for further evaluation.
- Endoscopic Esophageal Ultrasound (EUS) – Another similar procedure, this use of the ultrasound transducer is instead fed down the throat and into the esophagus which is located behind the windpipe. The esophagus is targeted in this test due to its proximity to specific lymph nodes in the chest. Also, as in similar testing, the tube allows for a hollow needle to be passed through it.
- Thoracentesis- Pleural effusion occurs when there is an accumulation of fluid around the lungs which typically occurs when cancer metastasizes into the lining of the lungs. This lining is known as the pleura. A sample is then taken for microscopic examination by inserting a thin needle into the chest between the ribs. Should a large amount of fluid be present this same procedure can also be used to remove some of that fluid, in turn improving the patient’s breathing.
- Thoracoscopy- Like a Thoracentesis this method requires a small incision through the chest in order to examine the pleural cavity. This test determines if cancer is evident in the space between the lungs and chest wall, as well as the pleura.
- Mediastinoscopy- This procedure is named for the mediastinum, which comprises the middle section of the chest cavity. The heart is contained in the mediastinum, as are all of the chest organs aside from the lungs. Mediastinoscopies require general anesthesia so that the doctor can make a small incision in the front of the neck just above the sternum. This incision allows for a small, hollow, lighted tube to be passed behind the sternum. This tube permits instruments to be passed through it in order to collect lymph node tissue samples located along the windpipe and other major bronchial tube areas.
- Video-assisted thoracoscopy(VATS)- The difference between this procedure and the aforementioned thoracoscopy is a VATS involves the collapsing of one lung which is done with the aid of a video device no larger than a pen. Collapsing the lung creates just enough space for this device to enter the chest cavity, allowing the doctor to visually inspect the surface of the lungs and chest wall. The biopsy is then performed through image guidance relayed on a video screen.
Other tests not involving tissue collection may also be required in order to arrive at a proper diagnosis. These tests vary in their combination and necessity on a case-by-case basis. They include blood tests, pulmonary function tests, and various imaging machines. Blood tests usually consist of a complete blood count in order to determine red blood, white blood, and platelet counts. Pulmonary function tests help determine a patient’s lung capacity and respiratory reserve. These factors influence the doctor’s assessment of the patient’s ability to tolerate specific surgeries or radiation treatment. Imaging tests use x-rays, radioactive particles, and other means in order to get more informative views of the body’s interior. Imaging tests can indicate of cancer is present, if and where a cancer has spread, or even to determine if treatment has been effective. There are multiple types of imaging tests as defined below:
- Chest X-ray- Traditionally the first test ordered when diagnosing lung cancer, a chest x-ray is a noninvasive procedure where film is taken of the chest and nearby structures. These images will then help the doctor to determine the presence of cancer and necessity of other testing.
- CT Scan- This test is another form of x-ray, producing a detailed cross-sectional image of the body. A CT scan takes several pictures where traditional x-rays take only one. Once the images have been compiled a computer combines them, concentrating on the portion being studied. A contrast solution is either ingested or delivered intravenously to better outline any abnormalities. CT scans are capable of spotting even small lung tumors, helping to determine a concrete location and severity of the tumor. CT scans are used for staging, learning the rate of spread, determining treatment options, and sometimes guiding biopsy needles.
- Positron Emission Tomography scan- Referred to as a PET scan this imaging test follows an injection of glucose containing a radioactive atom. Cancerous cells absorb radioactive sugar, even in the minute doses used for this test. This absorption allows doctors to see an image of revealing areas of radioactivity.
- Magnetic-Resonance Imaging Scan- Also known simply as an MRI, this scan utilizes strong magnets in lieu of x-rays, displaying a detailed image of soft tissues.
- Bone scan- As the name indicates, this test determines if cancer has spread to a patient’s bones. Intravenously, a radioactive material is injected and settles in any damaged area of bone. Special cameras associated with bone scans detect that radioactivity after taking pictures of the skeletal system.
Aside from testing, another important factor of diagnosis is collecting a comprehensive personal patient history including an extensive medical and family background. In addition to testing, this information helps doctors check not only for symptoms, but also for possible risk factors. Previous exposure to elements such as asbestos is the kind of vital information these personal histories call for, especially where lung cancer and mesothelioma are concerned. Questions concerning the patient’s general health and a physical exam are also commonplace. In most cases, these types of medical assessments are among the first steps to a proper diagnosis of lung cancer and other asbestos-induced illnesses and diseases.