Experts Review Management of Liver Metastases in Patients With Neuroendocrine Tumors

In a presentation at the 2021 annual meeting of the North American Neuroendocrine Tumor Society (NANETS), presenters reviewed cases for and against the use of surgical resection in the treatment of patients with neuroendocrine tumors (NETs) and liver metastases.

Panelist Gagandeep Singh, MD, FACS, presented the case in favor of surgery, arguing that the decision should not be based on what can be removed, but instead on what is left behind. According to the data presented, patients with liver metastases who received surgery resulting in 70% or greater debulking of the disease had improvements both in overall survival (OS) and progression-free survival (PFS) that were statistically and clinically significant compared to those who had less than 70% disease clearance following surgery.

Singh classified patients with liver metastases into 4 primary groups: those who had a solitary large metastasis, those who had multiple liver metastases but 70% disease resection was possible (often through the removal of a large primary metastases), those who had multiple diffuse metastases in which 70% removal would be impossible, and those for whom surgery serves primarily a palliative purpose. In his talk, he suggested that surgery should be used for patients in all categories save for category 3.

“I do believe surgery is the gold standard,” Singh said during the presentation. I do believe that taking out the primary tumor, whether it’s a PNET, or a small bowel, or a colon primary, we should definitely chase it down. We should clear the nodal metastases. I definitely think that resecting the liver, if you can achieve more than 70% clearance, is a good way to go.”

Singh did concede that there were cases that would make liver resection less of a viable option. While the current evidence suggests that patients with well-differentiated tumors of grades 1 or 2 have significant positive results from surgery, those with grade 3 tumors or poorly differentiated disease did not have considerable evidence suggesting surgical efficacy. Further, Singh indicated that extrahepatic tumor involvement, carcinoid heart disease, and peritoneal carcinomatosis should be considered contraindications to liver resection.

Presenting on the cases in which surgery is less of a viable option and medical management would be preferred, Callisia N. Clarke, MD, MS, FACS, FSSO, highlighted just how many treatment options were available for patients who had non-resectable disease. Liver-directed therapies included both ablative options—such as microwave ablation, radiofrequency ablation, and cryotherapy—and intraarterial options, such as bland embolization, chemoembolization, and ⁹⁰Yttrium transarterial radioembolization.

“We’re starting to see novel combinations of these therapies that are really extending the benefits of just the single therapy only,” Clarke said. “The HEPAR PLuS trial looked at PRRT in combination with embolization for patients with neuroendocrine tumors and saw significant improvement. We’re now starting to see the combination of targeted therapies with radioembolization as well, so there’s a lot more to come in the future for these patients.”

REFERENCE

NET Medical Session 4: Management of liver metastases in NETs. Presented at: North American Neuroendocrine Tumor Society (NANETS) 2021 NET Medical Symposium. November 6, 2021. Accessed November 6, 2021.