Safety and cost-effectiveness of immediate right hemicolectomy versus active surveillance for well-differentiated appendiceal neuroendocrine tumors 1-2 cm in size: a Markov decision analysis.

Purpose: Therapeutic management of appendiceal neuroendocrine neoplasms (a-NENs) 10-20 mm in size represents a challenge for both surgeons and oncologists. We compared active surveillance after appendectomy versus immediate right hemicolectomy (RHC).

Methods: A Markov decision model was developed based on literature parameters. The endpoints were the life expectancy, the quality-adjusted life expectancy (QALY), and the cost-effective ratio expressed by the incremental cost-effective ratio (ICER). A deterministic sample analysis (DSA) with one-way sensitivity analysis was performed for the base case scenario. A probabilistic sensitivity analysis (PSA) was performed to solve the uncertainty of the model. Montecarlo simulation with 100,000 replications for each arm was used. Data are reported in US$. The acceptability of the strategy was set 3 times ($130,049) the Euro area's gross domestic product per capita ($43,394).

Results: The 10-year survival rates for active surveillance and immediate RHC were 98.2 and 98.9%, respectively. The DSA showed the superiority of active surveillance versus immediate RHC (10 versus 9.0 QALY). Active surveillance costs more than immediate RHC ($35,761 vs. $39,486). The resulting ICER was $4302 per QALY. The model was more sensitive to the length of follow-up (99.9% variability): the longer the surveillance, the higher the ICER (spread $302,703). PSA analysis confirmed active surveillance as the most cost-effective choice, costing an ICER + $4059 per QALY.

Conclusion: Active surveillance is safe and cost-effective in patients with appendiceal NENs of 10-20 mm in size, both clinically and economically.