Factors confounding evaluation of treatment effect in lung cancer.

Disease extent, performance status (PS), and serum lactate dehydrogenase (LDH) are the most important prognostic factors in both inoperable non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Hyponatremia and serum alkaline phosphatase play an additional role in SCLC. Many different stratification algorithms have been proposed in SCLC but a general consensus cannot be achieved before it is decided whether stage of disease should rank above or be included in an algorithm, along with other prognostic factors.