What do Lung Cancer Stages Mean?
by Beth G. Hodges, MD

To understand the different lung cancer stages, it is important to first know about the types of lung cancer because names given to lung cancer stages vary depending on the specific type of lung cancer involved.

There are two main types of lung cancer, small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC.) The typing is based, as it sounds, on the size of the cells in the tumor. Conversely, staging is based on the size of the tumor itself.

SCLC comprises 20% of all tumor types and is the easiest to stage. Its stages are broken down simply into "limited," meaning all tumor confined to the chest, and "extensive," meaning tumor has spread to other parts of the body. It is the most aggressive type of lung cancer, with a median survival of only 2-4 months after diagnosis if left untreated (median survival means half (50%) of all victims will have died by that time).

Surgery is not an option for this type of cancer, as the cells tend to spread quickly, but it does respond moderately well to chemotherapy, which can increase survival by 4-5 times. Radiation therapy can also be helpful. Still, even with aggressive treatment, only 5-10% of those diagnosed are still alive at five years.

The second main type of lung cancer, comprising 70% of all lung cancers, is NSCLC. This type can be further broken down into large cell cancer (10%), adenocarcinoma (30-40%), and squamous cell carcinoma (30%). Carcinoid, lymphoma, and metastatic disease can also present as lung tumors, but are not part of this staging system.

Treatment of NSCLC usually first involves surgical removal of the local tumor. A Stage I tumor can be completely removed and has a 75% 5 year survival rate. As stages progress, radiation is utilized in therapy. It cures very few but can prolong survival and give relief of symptoms. Chemotherapy is used in advanced disease but the 5yr survival rate is less than 15%.

In NSCLC, stage I disease is confined to one lung with no spread to the other lung or to other parts of the body. Stage II usually indicates spread to other areas of the same lung and stage III disease has spread to the other lung. Stage IV indicates disease spread to other areas of the body or outside the lung sac via a fluid containing cancer cells (called a malignant pleural effusion.)

The additional staging classifications alluded to above are complex, but essentially break down tumors into subclasses by size of the tumor. The reason for the modification is to bring the U.S. staging system close to the European and Japanese systems and to open up more patients to treatment than previously. Remember, treatment protocols for lung cancer are based on the stage of the cancer and if someone is felt to have too advanced disease to benefit from the therapy versus the risks involved, therapy is withheld or altered.

More so than with some other types of cancer, proper staging of lung cancer is critical to directing therapy and in determining initial prognosis and should be undertaken with care.

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Sidebar:
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The staging system for lung cancer is rather complicated and became more so in August of 2009 with the 7th Edition TNM Staging System changes. The changes made to the previous system were based on data collected on 100,000 lung cancer cases from 46 centers in 19 countries. It is the first real change to this system in 20 years, and will change how some patients diagnosed with lung cancer (especially stage II and III non-small cell lung cancer) are treated.

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Published - September, 2009