Tumor Staging

  • Dr. Nwogu explains tumor staging to an RPCI patient

The Path to Precision Diagnosis

After lung cancer has been diagnosed, tests are done to find out if cancer cells have spread within the lungs or to other parts of the body. Pathology tests help to determine the stage and grade — two classifications that are essential to choosing the most effective cancer treatment and predicting how the disease will progress. 
 
There are three ways that cancer spreads in the body:
  • Through Tissue: Cancer invades the surrounding normal tissue.
  • Through the Lymph System: Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
  • Through the Blood: Cancer invades the veins and capillaries and travels through the blood to other places in the body.

When cancer cells break away from the primary (original) tumor and travel through the lymph or blood to other places in the body, another (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor. For example, if lung cancer spreads to the bones, the cancer cells in the bones are actually lung cancer cells. The disease is metastatic lung cancer, not bone cancer.

Tumor Staging

Staging is the process by which your cancer specialists determine how to treat your cancer and how far your cancer has spread. It takes into account the primary (original) tumor size, number of tumors and whether it has metastasized, or spread to the lymph nodes or distant parts of the body. Staging is based on the pathology report, physical exam and radiologic exams, such as x-rays, CT scans and MRIs. Generally, a lower stage indicates a better prognosis (e.g., the likely outcome or course of a disease; the chance of a full recovery or recurrence).

For Non-Small Cell Lung Cancer:

  • Occult Stage: Lung cancer cells are found in sputum or in a sample of water collected during bronchoscopy, but a tumor cannot be seen in the lung.
  • Stage 0: Cancer cells are found only in the innermost lining of the lung. Also called carcinoma in situ. The tumor is not an invasive cancer.
  • Stage IA: The lung tumor is an invasive cancer. It has grown through the innermost lining of the lung into deeper lung tissue. The tumor is no more than 3 centimeters across (less than 1 ¼ inches). It is surrounded by normal tissue and the tumor does not invade the bronchus. Cancer cells are not found in nearby lymph nodes.
  • Stage IB: The tumor is larger or has grown deeper, but cancer cells are not found in nearby lymph nodes. The lung tumor is one of the following:
    • The tumor is more than 3 centimeters across.
    • It has grown into the main bronchus.
    • It has grown through the lung into the pleura.
  • Stage IIA: The lung tumor is no more than 3 centimeters across. Cancer cells are found in nearby lymph nodes.
  • Stage IIB: The tumor is one of the following:
    • Cancer cells are not found in nearby lymph nodes, but the tumor has invaded the chest wall, diaphragm, pleura, main bronchus, or tissue that surrounds the heart.
    • Cancer cells are found in nearby lymph nodes, and one of the following:
      • The tumor is more than 3 centimeters across.
      • It has grown into the main bronchus.
      • It has grown through the lung into the pleura.
  • Stage IIIA: The tumor may be any size. Cancer cells are found in the lymph nodes near the lungs and bronchi, and in the lymph nodes between the lungs but on the same side of the chest as the lung tumor.
  • Stage IIIB: The tumor may be any size. Cancer cells are found on the opposite side of the chest from the lung tumor or in the neck. The tumor may have invaded nearby organs, such as the heart, esophagus, or trachea. More than one malignant growth may be found within the same lobe of the lung. The doctor may find cancer cells in the pleural fluid.
  • Stage IV: Malignant growths may be found in more than one lobe of the same lung or in the other lung. Or cancer cells may be found in other parts of the body, such as the brain, adrenal gland, liver, or bone. (Most Roswell Park patients who seek medical attention for lung cancer have advanced disease.)
Small cell lung cancers are staged using a two-tiered system: 
  • Limited-stage SCLC refers to cancer that is confined to its area of origin in the chest.
  • In extensive-stage SCLC, the cancer has spread beyond the chest to other parts of the body.
Sometimes, pictures and illustrations help us understand more completely. You can find pictures of the stages of lung cancer on the National Cancer Institute website

Lung Cancer Staging: Hope on the Horizon 

Chukwumere Nwogu, MD, of Roswell Park’s Department of Surgery, has been awarded grants from the National Cancer Institute and Thoracic Surgery Foundation totaling nearly $1.2 million to investigate the effectiveness of an intraoperative gamma probe in the staging of lung cancer. 

Accurate staging of lung cancer is an important criterion used to determine treatment following surgery. Current staging methods often lack sensitivity and specificity in early-stage lung cancer. This method will give surgeons a new tool to identify cancer metastases to lymph nodes with greater accuracy, which would then guide clinical decisions leading to more effective postsurgical treatment options.