Lung Cancer: An Overview

Lung Cancer is a type of cancer when the cells of the lungs begin to grow out of control. Lung Cancer is the most common cause of cancer in both men and women worldwide. About 90%-95% of lung cancers arise from epithelial cells, which have the lining of larger and smaller airways (bronchi and bronchioles); that’s why lung cancers are also known as bronchogenic cancers. Lung cancer includes both small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC), with a distribution of about 13% SCLC, and 84% are NSCLC.

What are the types of lung cancer?

Small-cell lung cancers (SCLC) and non-small-cell lung cancers (NSCLC), the classification simply depends upon the microscopic appearance of the tumor cells and the size of the cells.SCLC is about 20% of lung cancers. SCLC is related to cigarette smoking, with nearly 1% of these tumors occur in nonsmokers. NSCLC is about 80% of all lung cancers. NSCLC can be divided into many types.

• Adenocarcinomas (nearly 40%) is one of the most common types of lung cancer that occur in the outer, or peripheral, areas of the lungs.
• Squamous cell carcinomas (nearly 30%) known as epidermoid carcinomas, squamous that arise most frequently in the central chest area in the bronchi.
• Large cell carcinomas (nearly 10%) referred to as undifferentiated carcinomas, are the least common type of NSCLC.

Stages of Lung Cancer:

Stages tell how far it spread and help in treatment.

Non-small cell lung cancer has four main stages:

Stage 1: The tumor is in a single lung which is not spread to any lymph nodes or distant organs.

Stage 2: The size of cancer has grown to more than 3cm and may have the chance of spread to the lymph nodes within the lung but not to the distant organs.

Stage 3: The size of the cancer is much more nearly 7 cm across and may have spread to lymph nodes at the center of the chest but has not to any distant organs. Stage 3 has two subtypes:

•  3a: Cancer has not spread to the chest.

•  3b: Cancer has spread to lymph nodes of both the lungs or near the collar bone.

Stage 4: NSCLC has spread to both the lung, to the fluid around the lung or heart, to lymph nodes or other organs.

Small-cell lung cancer (SCLC) has two main stages:

In the limited stage, In this the cancer is found in lungs or lymph nodes of the chest.

The extensive stage means cancer has spread:

•  throughout one lung

•  to the opposite lung

•  to lymph nodes on the opposite side

•  to fluid around the lung

•  to bone marrow

•  to distant organs

What Causes Lung Cancer?

Anyone can have Lung Cancer but about 90% of cases of Lung Cancer are due to smoking. As you Inhale the smoke it starts damaging your lungs, Although Lungs have a capacity to repair but continuous exposure to smoke makes it difficult for the lungs. RADON gas is also one of the causes of Lung Cancer according to the American Lung Association.

Breathing of hazardous substances, over a long period of time, can also lead to lung cancer.

• throughout one lung
• to the opposite lung
• to lymph nodes on the opposite side
• to fluid around the lung
• to bone marrow
• to distant organs

Lung Cancer Signs and Symptoms:

• Respiratory symptoms include Wheezing, Coughing of Blood
• Systemic symptoms include Weight loss, Fever, Nail clubbing
• Non-specific symptoms include Weight loss, Weakness, and Fatigue
• Psychological symptoms include Depression and mood changes also are common.
• Symptoms due to the cancer mass are chest pain, bone pain, superior vena cava obstruction, or difficulty swallowing

What tests do physicians use to Diagnose Lung Cancer?

There is a wide range of diagnostic procedures and tests to diagnose lung cancer. The initial test includes X-ray, CT, MRI, and PET Scan.  After the initial test there is much more Specialised test for the Lung Cancer:

Bone scans: Used to examine the images of bones on a computer screen.

Sputum cytology: This is one of the most risk-free and inexpensive tissue diagnostic procedures, with one limitation since tumor cells will not always be present in sputum even if a cancer is present.

Bronchoscopy: To visualize the tumor fiberoptic probe passes through the nose or mouth which reveals the localization of the tumor that can be sampled.

Needle biopsy: Fine-needle aspiration (FNA) through the skin, is done to retrieve the cells for diagnosis of the tumor.

Thoracentesis: To diagnosis the accumulation of fluid in the space between the lungs and chest wall known as Pleural effusion.

Mediastinoscopy: Examining the chest cavity between the lungs

Molecular testing: Molecular genetic testing to look for genetic mutations in the tumor and testing may be done to look at changes in epithelial growth factor receptor (EGFR) and the ALK genes