Introduction: Gastroenteropancreatic neuroendocrine tumors (NETs) are uncommon tumors with a reported incidence of 2.5-5 per 100000 population. The recent classification system of NETs proposed by the European Neuroendocrine Tumor Society (ENETS) uses both Ki-67 labelling index and mitotic index to assign grade (low, intermediate, high). It has been adopted into routine practice but there is limited data on the relationship between these indices and their effect on classification.
Aim(s): To identify the relationship between Ki-67 labelling index and mitotic count.
Materials and methods: Two-hundred and fifty-three NET patients, 142 midgut and 111 pancreatic had their cases reviewed. Ki-67 proliferation index, identified by staining tumor sections with MIB-1 antibody, was determined by assessing the percentage of positively staining tumor cell nuclei in 2000 tumor cells in areas with highest degree of nuclear labelling where possible. Mitotic counts (per 10 hpf) were evaluated in at least 40 fields in areas of highest mitotic activity. Grades (1 to 3) according to the new TNM classification were assigned using both indices. Correlation (Spearman r) between Ki-67 and mitotic count was calculated. Weighted Kappas were calculated to measure agreement between grades assigned according to Ki-67 or mitotic count using Graphpad software.
Conference: 7th Annual ENETS Conference (2010)
Presenting Author: Dr Mohid S Khan
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