Expression of nerve growth factor receptors is correlated with progression and prognosis of human pancreatic cancer. 
The aim of the present study was to investigate the prognostic value of the two types of nerve growth factor receptors (NGFR), namely high-affinity receptor TrkA and low-affinity receptor p75NGFR, in pancreatic cancer.  The mRNA expression of NGFR for TrkA and p75NGFR was examined in 56 human primary pancreatic cancers using real-time quantitative reverse transcription-polymerase chain reaction.  Nerve growth factor (NGF) receptors were found in all tumor specimens.  It appears that the growth of pancreatic cancer cells stimulated by NGF depended on the expression levels and the ratio of TrkA to p75NGFR.  TrkA and p75NGFR were negatively correlated and both were associated with abdominal or back pain and perineural invasion.  Regarding this, patients with high TrkA expression levels exhibited more frequent perineural invasion and a higher degree of pain, whereas the results of p75NGFR were opposite.  For Cox univariate analyses in the overall survival study, high expression of p75NGFR was associated with longer overall survival, but TrkA exhibited opposite effects and included an effect on perineural invasion and pain.  Histoprognostic grading, tumor size and node involvement were not prognostic factors.  In Cox multivariate analyses, TrkA and p75NGFR were both prognostic parameters.  The present study found that the expression of TrkA in pancreatic cancer is a marker of tumor aggressiveness.  Conversely, we also found that elevated p75NGFR expression is associated with a favorable prognosis.  We demonstrated that NGF exerts both stimulatory and inhibitory effects on pancreatic cancers, with the overall effect determined by the expression levels and the ratio of TrkA to p75NGFR.