Objectives: Elevated neurokinin A (NKA) levels are associated with poor prognosis in patients with small bowel neuroendocrine tumors. We hypothesized that patients with NKA levels that remain elevated despite treatment with surgical cytoreduction have a poor prognosis.
Methods: Patients diagnosed with small bowel neuroendocrine tumors who underwent surgical cytoreduction at our institution were identified. Demographics, histopathologic characteristics, and biochemical data were collected. Patients were grouped by the trend of their NKA levels (group 1, continuously normal; group 2, transiently elevated but normalized after therapy; group 3, remained elevated despite therapy). Survival rates were calculated from the date of the patient's first NKA level.
Results: Serial NKA values after surgical cytoreduction were monitored in 267 patients. Kaplan-Meier 2-year, 5-year, and 10-year survival rates were as follows: group 1 (n = 157), 97%, 89%, and 62%; group 2 (n = 78), 99%, 90%, and 78%; and group 3 (n = 32), 88%, 69%, and 0%. Survival rates were statistically significant between groups 1 and 3 and between groups 2 and 3 (P < 0.01).
Conclusions: Serial monitoring of plasma NKA levels is useful in identifying patients who have a poor prognosis. Elevated NKA levels can indicate the need for immediate therapeutic intervention.