Evaluation of the concordance between the stage of the disease and Ki-67 proliferation index in gastroenteropancreatic neuroendocrine tumors

Abstract

This study aimed to determine the degree of concordance between TNM staging used in the determination of the prognosis of gastroenteropancreatic neuroendocrine tumor (GEP-NET) patients and the Ki-67 proliferation index value used in the grading of these tumors and investigate the most reliable prognostic parameter among them. The medical files of the patients with GEP-NET who were diagnosed or followed up in Erciyes University Faculty of Medicine were retrospectively examined and demographic characteristics, survival times, grade of these tumors, histopathologically detected Ki-67 values, and histopathological characteristics were recorded and evaluated statistically. The mean age (53.09±14.6 years; range, 16-85 years) of all (n=141) the patients was estimated. The patient population included 72 (51.1%) female and 69 (48.9%) male patients, with a male/female ratio of 0.95. The most frequently encountered primary sites were the stomach (33.3%), and then in decreasing oder of frequency the pancreas (27%), colon-rectum (15.6%), the small intestine (12.8%), and the appendix (11.3%). The GEP-NET of the patients was in grade 1 (G1) (n: 103; 73%), grade 2 (G2) (n: 24; 17%), and grade 3 (G3) (n: 14; 10%). The GEP-NET of the patients was stage I (n: 66; 46.8%), stage II (n: 14; 9.9%), stage III (n: 12; 8.5%), and stage IV (n: 49; 34.8%). In the statistical analysis, Ki-67 increased in parallel with the stage of the disease (P<0.001). As Ki-67 increased at a rate of 1%, survival rates of the patients decreased 1.027 times (P=0.01). Five-year survival rates of the patients were 88% in G1, 44% in G2, and 24% in G3. Patients in G2 and G3 had a 6.67 and 12.38 times lower chance of survival compared with G1 patients, respectively. Survival rates of stage IV patients were 5.6 times lower relative to stages I and II patients, respectively (P<0.001). The median 5-year survival rates of the patients were 90% in stage I, 100% in stage II, 47% in stage III, and 46% in stage IV. In univariate analysis, age of the patients, grade, stage of the tumor, and lymph node metastases were found to be parameters that affected overall survival, whereas no significant correlation was found between the sex of the patient and the primary organ from which the tumor originated and survival rates. However, in the multivariate analysis, survival rates decreased inversely with age, whereas no significant correlation was found between grade and stage of the tumor and survival rates. In conclusion, a decrease in the average survival rate in parallel with an increase in the grade of the tumor was more prominent compared with a decrease in survival rates in accordance with an increase in the stage of the tumor. This indicates that in the prediction of prognosis in patients with GEP-NET, the Ki-67 value can be a more important evaluation factor relative to staging.