What are the main types of lung cancer?

Lung cancer is categorized into two primary forms based on the type of tumour and its invasiveness.1

Small-Cell Lung Cancer

Small-cell lung cancer (SCLC), also known as oat-cell carcinoma, accounts for 10–20 percent of all cases. It is characterized by small, round, or oat-shaped cells and is considered the most aggressive form of the disease, often spreading rapidly before symptoms appear. It is rarely found in individuals who have never smoked.1

Non-Small-Cell Lung Cancer

Non-small-cell lung cancer (NSCLC) accounts for the remainder of cases and primarily consists of three types:1

• Adenocarcinoma: The most common type in the United States, accounting for about 40 percent of cases. These tumours often originate in the smaller, peripheral bronchi and form gland-like structures.1
• Squamous cell carcinoma: Also called epidermoid carcinoma, this type makes up 25 to 30 percent of primary lung cancers. It typically develops in the larger central bronchi and tends to remain localized longer than other types.1
• Large-cell carcinoma: Comprising about 10 percent of cases, these tumours can begin anywhere in the lung and generally grow very quickly.1