Impact of Delayed Surgery on Local Colorectal Neuroendocrine Tumors: Is Surveillance a Feasible Option?

Background. Guidelines for some pancreatic neuroendocrine tumors (NETs) have shifted towards active surveillance given the indolent nature of this malignancy. We sought to assess the safety of delayed surgery on colorectal NETs as a surrogate for surveillance. Methods. Resected, stage I, well-differentiated colorectal primary NETs included in the Surveillance, Epidemiology, and End Results Program from 2010 to 2020 were included. Demographics, interval from diagnosis to surgery, and disease-specific survival (DSS) were retrospectively analyzed. Clinical stage I patients in the National Cancer Database were then reviewed to assess the incidence of pathologic upstaging, as well as the impact of active surveillance on overall survival (OS). Results. Overall, 4275 patients met the inclusion criteria and 33 (0.8%) had disease-specific death; 61 (1.4%) patients had surgery > 6 months after diagnosis. Median DSS and overall follow-up were 34 and 68 months, respectively. Multivariable analysis demonstrated delayed surgery > 6 months (hazard ratio [HR] 4.82 [1.13-20.55], p = 0.033), male sex (HR 3.16 [1.43-7.03], p = 0.005), and age (HR 1.06 [1.03-1.10], p = < 0.001) were associated with increased risk, while having a rectal primary (HR 0.32 [0.15-0.68], p = 0.003) was protective; however, a > 6-month delay remained significant when analyzing rectal primaries alone (HR 4.5 [1-19.2], p = 0.044). Delay in surgery > 6 months was associated with a 14% (p = 0.0023) incidence of upstaging, while active surveillance was associated with decreased OS (HR 1.48 [1.02-2.13], p = 0.039) compared with upfront resection. Conclusions. Prolonged delays in surgery > 6 months for colorectal NETs were associated with decreased DSS and a significant risk of upstaging, suggesting that surveillance may not be appropriate even for stage I disease.