GPER1 and neoplasm: When only the BP-NEN data were considered, no significant differences in GPER expression were noted, regardless of patient characteristics, including sex, age, smoking status, tumour size, or the presence of lymph node or distant metastases; however, a significant decline in GPER expression was observed as tumour grading increased (mean IRS values ± standard error of the mean (S.E.M.): G1 histology, 2.061 ± 0.599; G2 histology, 1.518 ± 0.701; G3 histology, 0.306 ± 0.118; Kruskal–Wallis test, p = 0.001).