Influence of tumor stage, symptoms, and time of blood draw on serum concentrations of organochlorine compounds in exocrine pancreatic cancer.

BACKGROUND: Knowledge is scant on the relationships between pathophysiologic processes common during cancer progression and changes in blood concentrations of organochlorine compounds (OCs).
OBJECTIVE: To analyze the influence of tumor stage, cancer symptoms, and time of blood extraction on serum concentrations of OCs in exocrine pancreatic cancer (EPC).
METHODS: Subjects were 144 incident cases of EPC prospectively recruited in eastern Spain. Blood was drawn and face-to-face interviews with patients were conducted during hospital admission. Information on signs and symptoms was obtained from medical records and patient interviews. OCs were analyzed by high-resolution gas chromatography with electron-capture detection. General linear models were applied to analyze log-transformed OCs corrected for total lipids.
RESULTS: Lower concentrations of six of the seven OCs analyzed (p,p'-DDE, three polychlorinated biphenyls, hexachlorobenzene, and β-hexachlorocyclohexane) were observed in patients with cholestatic syndrome (jaundice, hypocholia, and choluria). The constitutional syndrome increased only p,p'-DDT. The lowering effect of the cholestatic syndrome was stronger than the increasing effect of the constitutional syndrome (fatigue, anorexia, and weight loss), except for p,p'-DDT. When symptoms were considered, stage had only weakly inverse relationships with OC levels. The effects of symptoms on p,p'-DDE, p,p'-DDT, and the three PCBs remained significant after adjusting by the interval from blood extraction to first symptom of EPC, and even when further adjusting by stage.
CONCLUSIONS: Restriction or adjustment by stage and timing of blood draw may be insufficient to prevent biases associated with cancer progression. Symptoms may enable investigators to assess disease-induced changes in lipophilic exposure biomarkers.