Lung cancer: Clinical sciences

Lung cancer, or bronchogenic carcinoma, is defined as a tumor originating in the lung parenchyma or within the bronchi. It typically arises from lung epithelial gene mutations due to long-term exposure to cancer-causing agents, mainly tobacco use, but also exposure to asbestos or radon. Based on histopathological findings, lung cancer is classified into two main groups, small cell lung cancer or SCLC, and non-small cell lung cancer or NSCLC, which includes adenocarcinoma, squamous cell carcinoma, large cell carcinoma, and bronchial carcinoid tumor.

If a patient presents with a chief concern suggesting lung cancer, first, you should perform an ABCDE assessment to determine whether the patient is unstable or stable. If the patient is unstable, with severe respiratory distress or hypotension, then you must first stabilize the patient's airway, breathing, and circulation. In severe cases, you may also need to intubate the patient. Next, obtain IV access, and, if needed, provide supplemental oxygen. Finally, don’t forget to put your patient on continuous vital sign monitoring, including heart rate, blood pressure, and pulse oximetry.

Alright, now let’s go back to the ABCDE assessment and discuss stable patients. First, obtain a focused history and physical examination; order labs like a CBC and CMP, and finally, order imaging, primarily a chest X-ray and chest CT scan.

Here’s a clinical pearl! Yearly lung cancer screening with CT scan is recommended for patients who are 50 to 80 years of age that currently smoke or 50 to 80 years of age who have quit smoking within the past 15 years, and have at least a 20 pack-year smoking history.

History typically reveals cough, shortness of breath, pleuritic chest pain, as well as unintentional weight loss, and fatigue. If the lung cancer invades surrounding blood vessels, the patient could report hemoptysis, or coughing up blood. Some patients may also have a history of recurrent episodes of pneumonia involving the same spot.

Next, check the patient’s history for occupational and environmental risk factors. The most important ones include tobacco use and asbestos exposure. Other risk factors that you should know include marijuana, cocaine, vaping with electronic cigarettes, as well as exposure to radon gas, and air pollution. But, that's not all! Underlying lung conditions, such as COPD, pulmonary fibrosis, and tuberculosis, can also increase the risk of lung cancer!

On the other hand, the physical examination findings in a patient with lung cancer are often non-specific, but might include tachypnea or distal extremity clubbing. The same goes for lab results, which are also non-specific but could reveal anemia, thrombocytopenia, low serum glucose, hypercalcemia, hyponatremia, and hypokalemia. Finally, the chest X-ray and CT scan will show a pulmonary nodule or mass.

Now, here’s a high-yield fact! Certain findings can give you clues as to the type of lung cancer. For instance, tumors located at the apex of the lung, called Pancoast tumors or superior sulcus tumors, can compress adjacent structures like the brachial plexus, leading to ipsilateral shoulder and arm pain, paresthesia, or even atrophy of the hand muscles; and can also compress sympathetic nerve fibers, leading to Horner syndrome with ipsilateral ptosis, miosis, and facial anhidrosis. Keep in mind that the majority of Pancoast tumors are adenocarcinomas.

Moreover, lung cancers may cause different paraneoplastic syndromes. For instance, squamous cell carcinomas may produce PTH-related peptide, which in turn can lead to hypercalcemia.