What is the potential growth rate range for a grade 2 pancreatic neuroendocrine tumor (PNET) with 5% tumor involvement that has metastasized to the liver?

From the Guidelines

For a grade 2 pancreatic neuroendocrine tumor (NET) with liver metastases and a Ki-67 proliferation index of 5%, the potential growth rate typically ranges from slow to moderate, with a growth rate of approximately 0.5-1 cm per year. The 5% Ki-67 index places this tumor in the middle of the grade 2 category (which spans 3-20%), suggesting it may behave less aggressively than higher-grade NETs but more aggressively than grade 1 tumors 1. Some key points to consider in the management of this condition include:

• The presence of liver metastases indicates the disease has already demonstrated its ability to spread, which is an important prognostic factor 1.
• Patients with this tumor profile often have a median progression-free survival of 9-23 months without treatment, though this can vary significantly based on tumor burden, distribution of metastases, and individual patient factors 1.
• Regular monitoring with imaging every 3-6 months is typically recommended to assess growth patterns, as some tumors may show periods of stability followed by more rapid growth.
• Treatment options including somatostatin analogs, targeted therapies, or peptide receptor radionuclide therapy may help control tumor growth and extend progression-free intervals 1. It's also important to note that the overall results show disease control rates between 30% and 80%, PFS 9-23 months and OS 19-53 months, and the results were significantly better in patients with certain characteristics 1.

From the Research

Potential Growth Rates for Grade 2 Pancreatic NET with Liver Metastases

• The growth rate of a grade 2 pancreatic neuroendocrine tumor (NET) that has spread to the liver can vary depending on several factors, including the tumor's Ki-67 index, liver tumor burden, and treatment approach 2, 3, 4.
• A study published in 2017 found that high liver tumor volume, high-grade tumor, and progressive disease were associated with worse overall survival in patients with metastatic pancreatic NETs 2.
• Another study published in 2021 found that somatostatin analogs exert antiproliferative activity in pancreatic NETs with Ki-67 ≥10%, particularly in grade 2 tumors, and when hepatic tumor load is ≤25% 3.
• The median progression-free survival (PFS) for patients with advanced, nonfunctioning, well-differentiated pancreatic NETs with Ki-67 ≥10% receiving first-line long-acting somatostatin analogs was 11.9 months (95% CI, 8.6-14.1) 3.
• A study published in 2014 found that resection of the primary tumor in patients with unresectable liver metastases was associated with improved survival, with a 5-year disease-specific survival of 82% compared to 50% in non-operated patients 4.

Factors Influencing Growth Rate

• Ki-67 index: A higher Ki-67 index is associated with a more aggressive tumor and faster growth rate 2, 3, 4.
• Liver tumor burden: A higher liver tumor burden is associated with a worse prognosis and faster growth rate 2, 3, 4.
• Treatment approach: The choice of treatment, including somatostatin analogs, targeted therapies, and systemic chemotherapy, can influence the growth rate of the tumor 2, 5, 3, 6.

Range of Potential Growth Rates

• Based on the available evidence, the potential growth rate of a grade 2 pancreatic NET with liver metastases can range from slow progression to rapid growth, depending on the individual patient's characteristics and treatment approach 2, 5, 3, 4, 6.
• The median PFS for patients with advanced pancreatic NETs receiving first-line treatment can range from 11.9 months to 14.2 months, depending on the treatment approach and patient characteristics 3.