Raised circulating Neurokinin A predicts prognosis in metastatic small bowel neuroendocrine tumours. Lowering Neurokinin A indicates improved prognosis

Background Assessing prognosis is important in patients with neuroendocrine tumours of the small bowel as disease progression and survival is variable. We previously identified raised Neurokinin A as an independent indicator of poor prognosis and have shown that prognosis worsens when circulating Neurokinin A rises 50ng/L. In the present study we have examined survival in relation to Neurokinin A concentrations. Methods Patients in whom Neurokinin A rose 50ng/L between January 1989 and December 2010 were identified. All circulating Neurokinin A concentrations were recorded and survival was followed up to 31 December 2014 or to death. Results Median survival, from the date when Neurokinin A was first 50ng/L was 11.1 (2.0-117.8) months if Neurokinin A remained 50ng/L and 72.4 (4.8-152.6) months when Neurokinin A was reduced below 50ng/L and controlled below that concentration for 3 months (P<0.001). Survival was significantly better for patients attending the neuroendocrine tumour specialist clinic than for those not attending (P=0.009). Comparing patients identified during 1989-2000, and those during 2001-2010, Neurokinin A was successfully reduced in the earlier period in 30.3% patients with median survival 23.2 (2.0-152.6) months and this improved in 58.1% with median survival of 43.3 (2.0-141.1) months in the later period (P=0.019). Significance was greater between the earlier and later periods when only patients attending the neuroendocrine tumour clinic were compared (P=0.016). Conclusions Circulating Neurokinin A50ng/L is a strong indicator of poor prognosis when Neurokinin A remains above this concentration. Lowering Neurokinin A below 50ng/L indicates a significant improvement in prognosis (P<0.001). This prognostic indicator reflects improved treatment and survival in more recent years.