Progesteron-induced blocking factor (PIBF): A potential novel tumour marker for screening and follow-up patients for gastrointestinal cancer

Background: PIBF has been associated with maternal immune-tolerance and its role increasingly considered as a causative factor of diminished cellular immune defense (inhibition of NK cell cytolysis and influence on TH2 cytokine dominance over TH1) in neoplastic diseases. Human primary tumors and metastases are positive by immuno-histochemical staining with anti-PIBF antibodies. The level of PIBF in body fluids (blood and urine) has been found to correlate with the size of the tumor mass and seems to be suitable for monitoring therapeutic effectiveness and predicting relapse and tumor progression.

Patients and methods: Forty-one patients with gastrointestinal and head-and neck cancers were included in the study. We have measured PIBF in serum and urine by competitive one-plate ELISA with antibodies against a 55 aa long PIBF peptide, developed in our laboratory. PIBF levels were determined before operative or other treatment interventions. The single primary endpoint of the study was association of serum PIBF levels of patients with cut-off values previously determined for healthy, unaffected individuals.

Results: Significant elevation of PIBF levels were seen in all but 5/41 neoplastic cases (4 cases with pancreatic cancer and 1 case with planocellular cc of the sublingual region). In cases, where postoperative values could be obtained, PIBF levels fall down below the cut-off levels. Conlcusion: PIBF seems an interesting candidate tumor marker for gastrointestinal neoplasms, however, pancreatic cancer, one of the most difficult target for early diagnosis among GI neoplasms is a matter of debate and subject to further studies.