They reported their findings in the latest issue of the Journal of Clinical Oncology.
A total of 136 patients, undergoing surgery from 1979 to 1998, were included in the trial.
The influence of tumor size, mitotic rate, vascular invasion, necrosis, metastases, and nuclear grade on disease-free survival (DFS) and disease-specific survival (DSS) were determined.
Cases were further grouped according to an existing proposed classification system.
They were then regrouped, on the basis of mitotic rate (< 2 mitoses per 50 high-power fields vs higher) and necrosis (present or absent), into low- and intermediate-grade groups.
The investigators found that ≤ 2 mitoses per 50 high-power fields, vascular invasion, size ≤ 2 cm, metastases, necrosis, and nuclear grade, correlated with DFS and DSS in univariate analysis.
By multivariate analysis, tumor necrosis and presence of metastases retained significance for DFS.
| Mitotic rate and tumor necrosis are prognostic factors.
| Journal of Clinical Oncology |
For DSS, only mitotic rate was a prognostic factor.
Among the 18 macroadenomas, 8 borderline tumors, and 48 low-grade carcinomas, there was no significant difference in DSS between any groups.
However, in evaluating the newly proposed groups, the differences in DFS and DSS between low- and intermediate-grade groups were found to be highly significant.
Author Steven N. Hochwald, of the University of Florida College of Medicine, Gainesville, said on behalf of his group, "Pancreatic endocrine neoplasms exhibit a spectrum of biologic behavior.
"The proposed benign (macroadenoma) and borderline groups contain potentially aggressive tumors."
"An alternative system, based on mitotic rate and necrosis, correlates strongly with survival without specifically designating any group as benign," he concluded.