The staging system for small cell lung cancer (SCLC) was developed in part because of the characteristics that set SCLC apart from the other forms of lung cancer, known collectively as non-small cell lung cancer. There are only two classifications that doctors work with when analyzing a case of SCLC: those classifications are termed limited, and extensive. Virtually all other forms of cancer have a four-step staging system that is much more sophisticated and complex than the protocol used for SCLC, but for a number of reasons two stages are all that is needed.
Small Cell Lung Cancer Treatment
Staging not only dictates the degree to which cancer has advanced, it also provides the guidelines for treatment. One of the unusual traits of small cell lung cancer is that surgery is rarely used to resect the tumor from the patient’s lung. SCLC almost always forms in one of the bronchi, those tubes that connect the two lungs with the windpipe. Surgery in that location is challenging but what is more impactful is the unfortunate fact that SCLC spreads to distant parts of the body early in the development of the disease. That means most diagnoses (about 2/3) are made when small cell lung cancer has already moved beyond the bronchus to other segments of the body, rendering surgery an ineffective tool.
It is also true that the small cell which characterizes SCLC, the so-called “oat cell,” is dramatically responsive to both chemotherapy and radiation. Chemotherapy in particular can be used to knock out all of the malignant cells even in an advanced stage of SCLC; accordingly, chemotherapy and radiation are the treatment options of choice in almost all cases of the disease. With little variation in treatment for a disease that is usually diagnosed in an advanced stage, only two staging classifications are needed.
Limited Small Cell Lung Cancer
This is the term for early SCLC. If the TNM four-point staging system were put alongside the staging system for SCLC, stages 1, 2 & 3 would fall into this category. Limited small cell lung cancer means that the disease remains on one side of the body, not having traveled to the other lung. If it has metastasized, the spread is limited to lymph nodes in the proximity of the original tumor. So for SCLC, the definition for the early stage of the disease already includes some spread to adjoining areas. In very early cases of limited SCLC doctors may attempt a surgical removal of the principal tumor.
Extensive Small Cell Lung Cancer
Extensive SCLC is the advanced stage of the disease. Patients with extensive SCLC have cancer that has spread to distant parts of the body and possibly into the other lung. Most cases are diagnosed at this stage because SCLC spreads so rapidly and does so very early in the onset process of the disease. Many people experience no overt lung cancer symptoms at all with SCLC until it has reached the extensive level. Treatment with chemotherapy and radiation is just as effective as with limited SCLC; the use of radiation is somewhat curtailed because the location of the malignancy does not fit into the exposure range of a single radiation treatment.
Some physicians will use the 4-step staging protocol with small cell lung cancer in order to more precisely define the location and maturity of the disease. Use of those classifications does little to alter the treatment options however; most patients are treated for extensive small cell lung cancer and all patients are treated with chemotherapy and radiation.