Non-small cell lung cancer (NSCLC) affects the majority of those diagnosed with lung cancer, accounting for approximately 87 percent of all cases. Exposure to asbestos is associated with an increased risk of all major histological types of lung cancer, including non-small cell lung cancer. Those who have experienced asbestos exposure and smoke cigarettes are at an even greater risk, as the combination has a synergistic effect that greatly increases a person's risk of developing lung cancer.

In comparison to small cell lung cancer (SCLC), the cells of NSCLC appear to be larger in size when viewed under a microscope. There are several types of NSCLC, which are named for the various types of cells found within the cancer:

• Squamous cell carcinoma, also known as epidermoid carcinoma, begins in squamous cells. These cells are thin and flat and have the appearance of fish scales. This type of NSCLC forms in the lining of the bronchial tubes and remains the most common type of lung cancer in men.
• Adenocarcinoma begins in the cells that compose the lining of the alveoli, which are glands that produce mucus. This form of NSCLC is the most common type of lung cancer in women, as well as among those who have never smoked cigarettes.
• Large-cell undifferentiated carcinoma forms near the surface (outer edges) of the lungs and may begin in several types of large cells.

There are other types of NSCLC that occur less commonly, including pleomorphic, salivary gland carcinoma, bronchioalveolar carcinoma, and unclassified carcinoma. Bronchioalveolar carcinoma is a rare subset of adenocarcinoma that forms near the air sacs.

Symptomatic Differences Between SCLC and NSCLC

There are a variety of symptoms associated with lung cancer in general, but some forms of lung cancer can lead to a group of very specific symptoms, which are often called "syndromes." Horner syndrome, which is associated with cancers that affect the upper region of the lungs, can occur with both small cell and non-small cell lung cancers. Some syndromes, however, are more commonly associated with NSCLC.

Certain paraneoplastic syndromes—which are health issues caused by substances (often hormone-like) produced by the cancer—are most commonly caused by NSCLC. Some of the more common paraneoplastic syndromes induced by NSCLC include:

• Blood clots
• Excessive growth of the breast in men (gynecomastia)
• Excessive growth of particular bones, especially in the finger tips
• High levels of calcium in the blood (hypercalcemia), which can lead weakness, dizziness, confusion, constipation, and frequent urination

Naturally, diagnosing NSCLC and SCLC cannot be done based on the presence of symptoms alone. A variety of tests and imaging scans are commonly used in the diagnosis of both forms of lung cancer. Prognosis and treatment options depend on factors such as the type and stage of the cancer, as well as the presence of symptoms and the patient's overall health.

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