Video

Pathologic Classification of Neuroendocrine Tumors

For High-Definition, Click

At the time of diagnosis, it is essential to ascertain the grade for neuroendocrine tumors (NETs), since response in high-grade disease is substantially inferior, notes Rodney F. Pommier, MD. This can be accomplished using mitotic counts and the Ki-67 proliferation marker. In general, a mitotic count less than 10 is characterized as low grade, between 10 and 20 is considered intermediate grade, and greater than 20 is indicated as a high-grade tumor. In general, patients with high-grade tumors receive treatment with platinum-based chemotherapy.

In addition to markers, pathologists examine cellular differentiation, suggests Diane Reidy-Lagunes, MD, MS. For well-differentiated tumors, the Ki-67 or mitotic counts are utilized to further determine the correct grade. Traditionally, a Ki-67 above 20% indicated a high-grade tumor. However, recent data suggest that a Ki-67 greater than 55% may be a more accurate indicator of poor prognosis, Reidy-Lagunes notes.

Panelists agree these classification systems have not yet been perfected. To adjust for this, Matthew H. Kulke, MD, suggests a certain degree of clinical judgment is needed to determine whether a patient is a good candidate for platinum-based therapy. To help with this process, Reidy-Lagunes recommends utilizing an octreotide scan. If positive, patients with a high Ki-67 do not usually respond to platinum-based therapy.

Related Videos
Pamela L. Kunz, MD, associate professor, internal medicine (medical oncology), Yale School of Medicine; director, Center for Gastrointestinal (GI) Cancers, chief, GI Medical Oncology, Smilow Cancer Hospital, Yale Cancer Center
Suneel Kamath, MD
Suneel Kamath, MD
Jennifer R. Eads, MD, physician lead, GI Cancer Research, director, National Clinical Trials Network, Abramson Cancer Center, University of Pennsylvania, associate professor, clinical medicine (hematology-oncology), Penn Medicine, Perelman Center for Advanced Medicine
Olivia Aranha, MD, PhD
Michael Iglesia, MD, PhD
Petros Grivas, MD, PhD; and Chandler Park, MD, MSc, FACP
Arndt Vogel, MD
Daniel M. Halperin, MD, associate professor, Department of Gastrointestinal Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center
Haeseong Park, MD, MPH