Objective: A highly sensitive SPE-liquid/liquid extraction RPLC method has been developed for the analysis of 6β-hydroxycortisol and cortisol in the urine of cancer patients. Methods: After SPE column purification and liquid-liquid extraction

the sample test solutions were analyzed with RPLC using a C18 analytical column. This improved analytical method has been validated for linearity

accuracy （recovery from urine）

repeatability （within-day and between-day precision）

specificity

sensitivity

and stability. This SPE-liquid/liquid extraction-RPLC is rapid

simple

accurate and reproducible. The technique is particularly useful for monitoring the CYP3A activity of cancer patients in clinical settings. The results are expressed as the ratio of 6β-hydroxycortisol to cortisol. Results: The CYP3A activity from a total of 153 samples was measured using this improved method. Considerable variation in the CYP3A activity of different cancer patients has been documented. Thus

personalized medical treatment based on the individual metabolic enzyme activity level is necessary. Conclusion: This new analytical method facilitates such individualized medical treatments.