Non-Small Cell Lung Cancer - Introduction

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Highlights	Diagnostic Tests	Investigative Agents
Introduction	Staging Systems	Resources
Causes	Treatment Options by Stages	References
Symptoms	Surgical Procedures	References
Risk Factors	Radiation Treatments
Lifestyle Changes	Chemotherapy Treatments

In addition, cancers in the lung may have spread from other sites, such as the breast, thyroid, or colon. In these cases, doctors name the cancer after its original location, such as "breast cancer with lung metastases."

Non-Small Cell Lung Cancers

Non-small cell lung cancers are categorized into three types:

Squamous cell carcinoma (also called epidermoid carcinoma)
Adenocarcinoma
Large cell carcinoma

These separate types are grouped together because, in the early stages before the cancers have spread, they all can be treated with surgery.

Squamous Cell Carcinoma. Squamous cells are formed from reserve cells. These are round cells that replace injured or damaged cells in the lining (the epithelium) of the bronchi, the major airways. Tumors formed from squamous cells are usually found in the center of the lung, either in a major lobe or in one of the main airway branches. They may grow to large sizes and form cavities in the lungs.

Click the icon to see an image of squamous cell carcinoma.

When squamous cell cancer spreads, it may travel to the bone, adrenal glands, liver, small intestine, and brain.

Squamous cell carcinoma is nearly always caused by smoking, and it used to be the most common cancer. It still makes up 25 - 30% of all lung cancers.

Adenocarcinoma. Adenocarcinomas usually start from the mucus-producing cells in the lung. About two-thirds of adenocarcinomas develop in the outer regions of the lung, while one-third develop in the center of the lung.

In 1965, 12% of lung cancers were adenocarcinomas. They are now estimated to account for 40% of all lung cancers and are the most common lung cancers in many countries. They are also the most common lung cancers in women, and their rates are increasing dramatically in men. Until recently, adenocarcinoma was only weakly linked to smoking. Experts now suggest, however, that the dramatic increase in this lung cancer type in recent decades may be due to low-tar, filtered cigarettes. People who smoke them draw tiny particles deeper into their lungs.