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Prognostic Tool for Advanced, Well-Differentiated Neuroendocrine Tumors Treated With a Somatostatin Analog


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In the GETNE-TRASGU study (Spanish Group of Neuroendocrine and Endocrine Tumors Treated With Analog of Somatostatin in Gastroenteropancreatic and Unknown Primary NETs) reported in the Journal of Clinical Oncology, Carmona-Bayonas et al developed a predictive model for progression-free survival in patients receiving somatostatin analog treatment for advanced, well-differentiated gastroenteropancreatic (GEP) neuroendocrine tumors.

"This nomogram may be useful when stratifying patients with neuroendocrine tumors in future trials. Furthermore, it could be a valuable tool for making treatment decisions in daily clinical practice.”
— Carmona-Bayonas et al

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Study Details

The study involved data from 438 patients in the Spanish Group of Neuroendocrine and Endocrine Tumors Registry (R-GETNE) as a derivation cohort and a validation cohort of 97 consecutive eligible patients from The Christie NHS Foundation Trust, Manchester. Eligibility criteria included GEP primary, Ki-67 of 20% or less, and first-line somatostatin analog monotherapy for advanced disease. An multivariate accelerated failure time model was used to predict progression-free survival, with analysis deriving a time ratio (TR) value for covariates (TR > 1 indicates that the factor prolongs time to event; TR < 1 indicates greater likelihood of earlier occurrence).

Predictive Model

Median progression-free survival was 28.7 months and median overall survival was 85.9 months in the derivation cohort. A total of nine covariates were significantly associated with progression-free survival in the derivation cohort and included in the model: primary tumor location (eg, TR = 1.89, P < .001, for small intestine vs pancreas, gastric), Ki-67 percentage (eg, TR = 0.68, P < .001 for 8% vs 2%), neutrophil to lymphocyte ratio (eg, TR = 1.45, P = .026, for two vs eight), alkaline phosphatase (eg, TR = 0.61, P = .015, for greather than twice the upper limit of normal), extent of liver involvement (eg, TRs = 0.67, P = .013, for 25–50 metastases, and 0.54, P = .001, for > 50 vs none), presence of bone metastases (TR = 0.63, P = .013), presence of peritoneal metastases (TR = 0.63, P = .002), documented progression status before somatostatin analog treatment (eg, TR = 1.65, P = .015, for stable disease ≥ 3 months), and presence of symptoms when starting somatostatin analog treatment (eg, TR = 1.57, P = .001, for asymptomatic status).

KEY POINTS

  • Factors included in the model were primary tumor location, Ki-67 percentage, neutrophil to lymphocyte ratio, alkaline phosphatase, extent of liver involvement, bone and peritoneal metastases, documented progression status, and presence of symptoms.
  • C-index values were 0.714 in the derivation cohort and 0.732 in the validation cohort.

 

The model showed adequate calibration and fair discriminatory ability with a C-index of 0.714 (95% confidence interval [CI] = 0.680–0.747) in the derivation cohort and 0.732 (95% CI = 0.658–0.806) in the validation cohort. A web-based calculator for the model has been designed and is now available online.

The investigators concluded, “The GETNE-TRASGU evidence-based prognostic tool stratifies patients with GEP neuroendocrine tumors receiving [somatostatin analog] treatment according to their estimated [progression-free survival]. This nomogram may be useful when stratifying patients with neuroendocrine tumors in future trials. Furthermore, it could be a valuable tool for making treatment decisions in daily clinical practice.”

Alberto Carmona-Bayonas, MD, PhD, of the Hematology and Medical Oncology Department, Hospital Universitario Morales Meseguer, Universidad de Murcia, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was funded by a grant from Novartis. For full disclosures of the study authors, visit jco.ascopubs.org.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
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