Octreotide LAR dosage and survival among elderly patients with distant-stage neuroendocrine tumors.

Abstract

392 Background: Octreotide long-acting repeatable (LAR) is approved for the management of symptoms due to carcinoid syndrome and may delay tumor progression among patients with neuroendocrine tumors (NETs). It is unknown whether dosage of octreotide LAR has an impact on survival. The current analysis evaluates the impact of initial octreotide LAR dosage on survival of elderly patients with NETs. Methods: Distant stage NET patients diagnosed between 1/1999 and 12/2009 who had received octreotide LAR treatment within 12 months of diagnosis were identified from the SEER-Medicare database. Those under age 65, enrolled in HMOs, or without continuous enrollment in Medicare Parts A and B were excluded. We compared the five-year survival of NET patients based on dose per 28 days averaged over the initial 3 months: Group A, <= 20 mg; B, 21 to 30 mg; C, > 30 mg. Kaplan-Meier estimations and Cox proportional hazard modeling were used to examine the association between octreotide LAR dose and survival. Results: Among 214 distant stage patients (mean and median age at 74 years old) with octreotide LAR treatment, 73 (34%) received <= 20 mg, 82 (38%) received 21 – 30 mg, while 59 (28%) received >30 mg. Median survival for patients who received low, medium and high dosage levels were 20.8 (95% CI: 13.2 – 31.5), 32.6 (95% CI: 20.5 – 51.1), and 36.3 (95% CI: 24.8 – N/A) months respectively. The log rank test had a p-value of 0.006. Multivariate analyses showed that higher octreotide LAR dosage levels were associated with significant survival improvement for distant stage patients. Compared to patients with the low dosage level, patients with medium dosage (HR=0.52, P=0.002) and patients with high dosage (HR=0.48, P=0.004) had better five-year survival. The difference in survival between Groups B and C was not statistically significant. Conclusions: This population-based study suggests potential survival benefits for octreotide LAR 30 mg dosage level among elderly distant stage NET patients.