Staging in cancer is the process which indicates the extent of damage done by the cancerous cells. It helps the doctors to understand how early or advanced the cancer is. Once diagnosed, the staging of cancer helps doctors to plan the treatment as well as track the patient’s progress during and after the procedures. Staging also helps doctors and scientists to work out survival rates. It includes the tumor’s size, whether cancer has metastasized, and the organs it has spread to.

Staging for lung cancer is different and distinct for the two types of cancer; small cell lung cancer and non-small cell lung cancer.

Small cell lung cancer and staging (SCLC)
Small cell and non-small cell lung cancers are the two major types of lung cancer. SCLC incidents are about 15% of the total number of lung cancer cases. It starts in the bronchi but can also occur in the periphery of the lungs. If left untreated, it can spread at a rapid rate. Smokers are at high risk for SCLC. There is currently no tool or test that helps in the early screening of SCLC. Apart from imaging tests, it is diagnosed and staged using sputum cytology, bronchoscopy, ultrasound, needle biopsy, and thoracentesis.

SCLC is usually staged as limited or extensive.

• Limited staging indicates that the cancer is limited to one side of the chest or one part of the lung.
• Extensive indicates that cancer has spread through the lungs entirely and/or to the other parts of the body.

Non-small cell lung cancer and staging (NSCLC)
NSCLC always begins in the lung tissue and is classified into three types:

• Adenocarcinomas:  It starts in the periphery of the lungs.
• Squamous cell carcinomas:  It starts in the center of the lungs.
• Large cell carcinomas:  It starts in the lung tissue.

These cancers are grouped together because the staging, prognosis, and treatment are almost similar. They form about 85% of the total lung cancer cases.

Unlike SCLC, these cancers are staged differently. The stages are represented in Roman numerals from I to IV. The higher the number, the more advanced the cancer is. Stage III is further classified into Stage IIIA and IIIB.

Staging is determined based on physical exams and imaging tests like chest X-ray, CT scan and PET scan. Needle biopsy is also done on patients to recover tissues from the affected area, which are then tested.

What do the stages denote?

• Stage I: The cancer is present only in the lung tissue and the lymph nodes are not affected.
• Stage II: The cancer is present in the lung and has spread to the lymph nodes.
• Stage III:  The cancer is present in the lung, lymph nodes and in the middle of the chest.
• Stage IIIA:  Cancer has spread to the lymph nodes in the side of the chest where it started.
• Stage IIIB:  Cancer has spread to the lymph nodes on the opposite side of the chest.
• Stage IV:  Cancer has spread to both sides of the lungs and there is fluid around the lungs, or cancer has spread to the fluid around the heart.

Stage I and II are rarely detected, as lung cancer symptoms do not show until cancer has spread and advanced to stage III or IV. The earlier stages can be detected if people facing a high risk of cancer, particularly smokers, go for periodic screening.

How advanced is stage III lung cancer?
Doctors determine that a patient is in the III stage of lung cancer if:

• The size of the tumor is 3 cms or more.

• The tumor has spread to the lymph nodes in the chest.

• The tumor has spread outside the lungs and has affected other organs.

Stage IIIA and B have distinctive characteristics. However, treatment and outlook for IIIA and IIIB can be similar. It is important to be informed that there is not one generalized format of treatment for patients who are at Stage III of lung cancer. There will be some differences in treatment protocol based on the size, location of the tumor, age, and overall health of the patient.

A tumor is considered to be Stage IIIA in the following cases:

• If the tumors are large and have reached the lymph nodes near the lungs.
• If the tumors are small but have spread to lymph nodes away from the lungs.
• The cancer is on the same side as primary cancer.

A tumor is considered to be Stage III B in the following cases:

• If the tumor, big or small, has spread to lymph nodes that are far from the lungs.
• If the tumor has spread to other organs like the heart, or the esophagus, or to the collarbone.

It is estimated that about 30% of the people affected with lung cancer are diagnosed at Stage I and II. 30% are diagnosed when cancer has already reached stage III. The remaining 40% are diagnosed when lung cancer reaches stage IV, which is the most advanced stage.

Accurate diagnosis and staging are extremely crucial as they form the basis of treatment procedures availed.