If your doctors suspect lung cancer or need to evaluate your case further, you will probably need many studies in the process. Even after diagnosing and staging lung cancer properly, you still need more exams every now and then to make sure that everything is turning out as expected and detect potential problems before they turn into complications.
The variety of exams and workup tests for lung cancer include different categories, and we’re covering the majority in this article.
The most common imaging study is chest radiography, which typically shows a nodule or mass in one or both lungs. Other findings in chest radiography include enlargement of the mediastinum or helium, atelectasis, and pleural effusions.
When this type of lesion is encountered and follow-up patients with active disease, other studies are recommended. A chest CT-scan is one of the most common and particularly useful for staging. This imaging study can detect lymph node enlargement more accurately and other alterations in soft tissues. Depending on the stage, you might also need a CT scan of the upper abdomen focused on the adrenal glands and the liver, commonly affected by metastasis. A brain CT scan and magnetic resonance is also recommended, but only in patients with neurologic symptoms.
Magnetic resonance of the chest and spinal column is not always necessary unless patients display neurologic symptoms. In these cases, doctors want to rule out spinal cord compression or metastasis in the central nervous system.
But if the main focus is ruling out bone metastasis, one of the best studies is known as bone scintigraphy. This exam evaluates the bone tissue and looks similar to X-rays but highlighting the potential sites of bone metastasis in a darker color.
Similarly, a PET scan is very sensitive to diagnosing malignancies by evaluating the tissues’ metabolic activity. It is helpful to assess solitary pulmonary nodules and other suspicious findings that have not been confirmed yet. This exam is instrumental in searching for metastasis throughout the body, and it is more valuable than a CT scan to evaluate the mediastinum when it is affected by the disease.
Cancer is a multi-organ disease, especially in the late-stage. Thus, laboratory studies are often necessary before and after starting cancer therapy.
A complete blood count is useful at the moment of the diagnosis to evaluate your condition before starting chemotherapy. It is imperative throughout the disease in patients with metastatic lung cancer because one of the metastatic regions is the bone and bone marrow. Thus, metastasis can trigger anemia, neutropenia, and other blood cell abnormalities.
Other important laboratory studies include liver function tests, creatinine, blood urea nitrogen, magnesium, calcium, and serum electrolytes. They provide a valuable prognosis for these patients and help doctors detect paraneoplastic syndromes or suspect a metastasis case.
In emergencies when your breathing is severely affected, an arterial blood gas measurement will help detect and treat respiratory failure and its metabolic complications.
Cytologic Studies and Biopsies
This study category refers to the analysis of samples under the microscope, which may come from the sputum or a biopsy.
Sputum cytologic studies are not expensive and provide a quick answer in patients with a suspicious nodule or symptoms. However, it does have a very high false-negative rate of 40%. In other words, many patients who actually have lung cancer will have a negative result because their cancer is either not near the respiratory tract or not releasing enough cancer cells to detect them in cytology. For cytologic studies to increase their accuracy, several samples should be taken instead of one, and they should be preserved and processed appropriately.
Another sample taken to the microscope is collected in a needle thoracentesis or pleural fluid cytology in patients with pleural effusion and significant respiratory problems. This method is very sensitive and specific, but having a pleural effusion is by itself an ominous sign of lung cancer, and it is probably a high-risk disease.
On the other hand, a biopsy is usually made through a bronchoscope. Another option in peripheral tumors would be through a transthoracic needle biopsy. Either way, this is a direct sample of the tumor, and it is more reliable. Depending on the technique and the site of the lesion, biopsies can have a variable false-negative rate.
More invasive procedures provide a more accurate assessment of the lesion and direct visualization of the tumor, which helps evaluate the severity of the obstruction and collect tumor samples.
One of the most common invasive procedures in lung cancer is a bronchoscopy, but this procedure is only valuable for central lesions, those located near the airways. When the tumor is located in the periphery and far from the main airways, a bronchoscopy won’t find anything in particular. This procedure is often used to take a biopsy sample.
When bronchoscopy is not applicable, thoracoscopy can help obtain a biopsy sample. This is a minimally-invasive procedure that evaluates the pleura and the outer surface of the lungs. It is a safe procedure with minimal risks.
Tests and Workup For Special Groups
Tests and workup for lung cancer depend on your symptoms and how the disease progresses in your particular case. It also depends on any baseline health problem that you have. Specific populations may need special tests to decide what to do next:
- In patients with metastasis to the central nervous system, a head CT-scan is performed to evaluate the mass and consult the treatment options with the neurosurgeon.
- In immunosuppressed patients, frequent complete blood counts and electrolyte levels are useful to prevent complications
- In patients with intestinal pseudo-obstruction, electrolyte levels are also essential to correct the problem.
Farago, A. F., & Keane, F. K. (2018). Current standards for clinical management of small cell lung cancer. Translational lung cancer research, 7(1), 69.
Herbst, R. S., Morgensztern, D., & Boshoff, C. (2018). The biology and management of non-small cell lung cancer. Nature, 553(7689), 446-454.