From the Guidelines
The growth rate of a grade 2 pancreatic neuroendocrine tumor (NET) that has metastasized to the liver typically ranges from 2% to 20% per year, as measured by Ki-67 proliferation index. Grade 2 pancreatic NETs are moderately differentiated tumors with intermediate growth characteristics, falling between the slow-growing grade 1 tumors (Ki-67 <3%) and the aggressive grade 3 tumors (Ki-67 >20%) 1. When these tumors spread to the liver, the growth rate can vary significantly between patients, with some experiencing relatively stable disease for years while others see more rapid progression. Factors affecting growth rate include the specific cellular characteristics of the tumor, patient's overall health status, presence of functional hormonal symptoms, and response to treatments.
The tumor doubling time for grade 2 pancreatic NETs with liver metastases typically ranges from 6 months to several years. Regular monitoring with imaging every 3-6 months is usually recommended to assess growth patterns, as individual tumors can sometimes behave unpredictably despite their grade classification 1. Understanding the specific growth rate of a patient's tumor is crucial for determining appropriate treatment timing and selection. Some key points to consider when evaluating the growth rate of a grade 2 pancreatic NET with liver metastases include:
- The Ki-67 proliferation index, which is a key factor in determining the grade of the tumor and its potential growth rate 1
- The presence of somatostatin receptors, which can affect the tumor's response to certain treatments 1
- The patient's overall health status and presence of functional hormonal symptoms, which can impact the tumor's growth rate and the patient's quality of life 1
- The potential benefits and risks of different treatment options, including somatostatin analogs, peptide-receptor radionuclide therapy, and chemotherapy 1.
From the Research
Potential Growth Rates of Grade 2 Pancreatic Neuroendocrine Tumors with Liver Metastases
- The growth rate of grade 2 pancreatic neuroendocrine tumors (PNETs) with liver metastases can vary depending on several factors, including tumor grade, hepatic tumor load, and treatment approach 2.
- A study published in 2021 found that the median progression-free survival (PFS) for patients with grade 2 PNETs and liver metastases treated with somatostatin analogs was 11.9 months, with a range of 8.6-14.1 months 2.
- Another study published in 2025 found that the use of long-acting somatostatin analogs in patients with resectable PNETs who were not candidates for surgery due to high-risk surgical profile resulted in a median overall survival of 68.5 months, with a range of 60-99 months 3.
- The growth rate of PNETs can be influenced by the hepatic tumor load, with higher tumor burdens associated with shorter PFS and overall survival 2, 4.
- The treatment approach, including the use of somatostatin analogs, targeted therapies, and liver-directed therapies, can also impact the growth rate of PNETs with liver metastases 5, 6, 4.
Factors Influencing Growth Rate
- Tumor grade: Higher-grade tumors tend to have faster growth rates 2.
- Hepatic tumor load: Higher tumor burdens are associated with shorter PFS and overall survival 2, 4.
- Treatment approach: The use of somatostatin analogs, targeted therapies, and liver-directed therapies can impact the growth rate of PNETs with liver metastases 5, 6, 4.
- Liver metastases: The presence of liver metastases is a significant prognostic factor for PNETs, with liver failure being a common cause of death in patients with hepatic metastases 4.