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Various evaluation methods are available for aiding clinicians in lung cancer management. Some of these methods are highly specific. However, they are also invasive and burdened by non-negligible complication rates (e.g., mediastinoscopy); other methods are highly accurate and noninvasive, but require expensive equipment and well-trained personnel (e.g., PET scanning); others are fast, inexpensive and safe. However, their diagnostic yield is low and requires further clinical testing (an example of such tests is the chest-x-ray film). There is probably only one way to perform an easy, inexpensive, repeatable test, which is also fairly accurate and predictive. This is tumor marker testing, which - as a large and specialized literature shows - can be highly effective when based on a cytokeratin-derived marker assay.