Preanalytical aspects: a neglected issue.

Considerable research data is available that demonstrate that tissues are under tremendous biological stress when surgically separated from the body. This stress significantly changes gene and protein expression profiles, including activation or inhibition of signalling pathways and their receptors. Many of those are possibly involved in growth regulation and might serve as targets or stratification markers for new drugs. Factors that affect tissue dependent cancer research for target discovery and drug development include drug treatment and anesthesia of patients before surgical tissue removal, intrasurgical ischemia by ligation of main arteries, "cold" ischemia, i.e. the time interval between surgical removal and fixation of tissue, location of tumor biopsy within a given tumor, processing of tissue and fixation protocols and the availability of comprehensive clinical data. Controlled and rapid tissue processing is a prerequisite for understanding biological differences of patient tumors and to utilize these findings (e.g., cancer pathway activity) for targeted molecular therapies.