Difference in survival between right- versus left-sided colorectal neuroendocrine neoplasms.

Neuroendocrine neoplasms (NENs) are a heterogeneous group of tumors that arise from neuroendocrine cells, and in some cases are capable of producing agents that may cause characteristic hormonal syndromes (Cives and Strosberg, 2018). Such tumors were previously thought to be rare, but the rate of detection of NENs, especially from the gastrointestinal tract, is increasing with the widespread use of colonoscopy, cross-sectional imaging, and biomarkers (Gu et al., 2019). A study based on the Surveillance, Epidemiology, and End Results (SEER) database showed that the age-adjusted incidence of NENs increased 6.4-fold from 1973 (1.09 per 100 000) to 2012 (6.98 per 100 000) (Dasari et al., 2017), while there was a progressive increase in the incidence of colorectal NENs (Starzyńska et al., 2017).