There is a wide array of procedures for Lung Cancer Diagnosis. The physician considers the over-all health condition of the patient and the accuracy of the diagnostic procedure in choosing the most suitable method. Early detection is a vital factor in eliminating the disease once it has developed.

Lung cancer is categorized according to the aberrant cell. Lung cancer types are:

1.    Small cell carcinoma is sometimes called oat cell carcinoma due to its distinct flat cell shape. Approximately 13% to 15 % of lung cancers are in this category. Due to its rapid growth, it has a greater tendency to metastasize. However it is more responsive to chemotherapy and radiation than other forms of lung cancer.

2.    Non small cell carcinoma grows more slowly and is less sensitive to chemotherapy compared to small cell carcinoma. This cancer accounts for 85% to 87% of lung cancers. It is subdivided into three types:

1. Large cell carcinoma is also called undifferentiated carcinoma. It is a fast growing tumor that usually develops peripherally.
2. Squamous cell carcinoma is also called epidermoid. It tends to arise centrally, commonly in the segmental and subsegmantal bronchi.
3. Adenocarcinoma presents itself as peripheral masses or nodules.

Factors associated with lung cancer are generally due to one's lifestyle, environmental and occupational exposure. Anyone can be at risk. Unfortunately, screening which is done to detect lung cancer on its early stage ( see Lung Cancer Stages) is limited only to high risk populations. This is due to the radiation that is emitted from the screening procedure may actually cause formation of cancer. Eventually, the American College of Chest Physicians decided against the lung cancer screening due to its ineffectiveness.

During its early stage, lung cancer usually lacks any symptoms which makes early Lung Cancer Diagnosis a chalenge. The most frequent sign of lung cancer is chronic cough which the patient frequently ignores and attributes it to respiratory infections. It is not uncommon to detect the disease when it is in its late stage already.  A heavy smoker should suspect the development of cancer once pulmonary signs and symptoms arise.

There are various methods that aid in lung cancer diagnosis:

1.Chest x-ray provides a graphical picture of the lungs, its surrounding structures and any suspicious areas. However, it does not detect cancerous areas.

2. Computed tomography (CT) scan and positron-emission tomography (PET) scan may be indicated when the lung cancer tumor is hidden by other structures or if the nodules are too small to be seen in the x-ray. While both scans provide lung cancer pictures, PET scan can determine if the lung cancer tumor is actively growing. PET scan can also specify the type of cells in the tumor.

3. Bronchoscopy refers to the direct visualization of the structures. It involves a flexible scope inserted into the windpipe through the mouth or nose. It allows collection of tissue samples for biopsy.

4. Needle aspiration is usually performed if the location of the lung cancer tumor is not suitable for bronchoscopy. In this procedure, a fine needle is inserted through the chest wall. The needle is used to aspirate tissue sample of the tumor for biopsy.

5. Biopsy involves examination of tissue samples under the microscope. It is done to detect the presence and the type of cancer cells.

Sputum cytology is done by expectoration of phlegm. The phlegm is then examined under the microscope to look for any cancer cells. Although it is a cost effective diagnostic procedure, it is often unreliable as the tumor cells are not always present in the sputum even if there a cancer is present.