What is lung cancer?
This article was last reviewed and updated on July 31, 2019.
by Jason Wasserman, MD PhD FRCPC
Normal lung tissue
The lungs are large organs found in our chest. Normally a person has two lungs, one on each side of their body. Each lung is divided into parts called lobes. The left lung has two lobes called the upper and lower lobes. The right lung has three lobes called the upper, middle and lower lobes.
Air fills our lungs when we inhale and leaves our lungs when we exhale. The air enters our body through the nose and mouth and travels to the lungs down long hollow tubes called airways. The larger airways in the lungs are lined by special cells called squamous cells. These cells form a barrier on the inner surface of the airway called the epithelium.
The lungs are made up of thousands of small air-filled spaces. These air-filled spaces are lined by a single layer of specialized cells called pneumocytes.
What is lung cancer?
Cancer is a word used to describe a disease made up of abnormal cells that can increase in number faster than normal cells, damage or destroy surrounding normal tissue, and travel (metastasize) to other parts of the body.
Lung cancer is a category of disease that includes any type of cancer that starts from cells normally found in the airways or the lung. Within this category there are different types of lung cancer and your prognosis and treatment options will depend on the specific type of lung cancer seen by your pathologist.
Most types of lung cancer start from either the squamous cells in the large airways or the pneumocytes in the air spaces.
Types of lung cancer
The three most common types of lung cancer are called adenocarcinoma, squamous cell carcinoma, and small cell carcinoma. Non-small cell lung cancer is a category of lung cancer that includes both adenocarcinoma and squamous cell carcinoma.
Most lung cancers are diagnosed after a procedure called a fine needle aspiration or biopsy is performed to remove a small sample of tissue from an abnormal area in the lung. The tissue is then sent to a pathologist who examines it under the microscope. If cancer is seen in the tissue sample, your pathologist will determine the type of cancer.
Your pathology report after surgery
Most patients with lung cancer will undergo surgery to remove the tumour. Some patients will also be offered radiation therapy or chemotherapy before or after the surgery is performed. If you have surgery to remove the tumour from your body, the entire tumour will be sent to a pathologist for examination. In addition to the tumour, other tissues may also be removed and sent to pathology although the amount of additional tissue removed will depend on your diagnosis.
Once the entire tumour has been removed, your pathologist will determine the size of the tumour and look to see if the tumour cells have spread to any lymph nodes in or around the lung. Your pathologist will also closely examine the cut edges of the tissue (the margins) to make sure that no tumour cells were left inside your body.
Learn more about the most common types of lung cancer: