Survival benefits of radical resection of pancreatic neuroendocrine tumors (PNETs) in the presence of liver metastases are significantly lower among patients with poorly differentiated pancreatic neuroendocrine carcinoma (PNEC) grade 3 tumors than other tumor grades, according to findings (NET Abstract #C19) presented at the 7th Annual Neuroendocrine Tumors (NET) conference in Nashville, TN. The meeting was organized by the North American Neuroendocrine Tumors Society (NANETS).

“Among 93 patients who underwent surgical resection, the presence of PNEC grade 3 was the only factor independently associated with a poorer survival after surgery [median OS: 35 vs. 97 months; P<0.0001],” reported lead author Stefano Partelli, MD, of the Pancreatic Surgery Unit at the University Hospital of Ancona in Ancona, Italy, and colleagues.

“Radical surgical resection of PNET with liver metastases is associated with a significant benefit although surgery should be reserved to well- or moderately differentiated forms,” they concluded.

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The benefits of surgical resection of PNETs with liver metastases has been controversial. The coauthors evaluated outcomes for 169 patients diagnosed with stage IV PNET during 2000 to 2011 in four European cancer centers.

Fifty-seven percent of the tumors were PNET grade 2; 24% were PNET grade 1 and 19% were PNEC grade 3. Liver metastases were “mainly bilobar” (83%).

“Patients were divided into 3 groups (R0 resection group [resection for complete remission], R1/R2 resection group [resection to micro- or macroscopic tumor residuals], and no-resection group),” Dr. Partelli and coauthors reported. “Overall 19 patients (11%) underwent R0 resection, 74 patients (44%) underwent R1/R2 resection, and 76 patients (45%) underwent only medical treatment.”

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Median overall survival (OS) from time of diagnosis was 73 months, the researchers reported. (1-year, 2-year and 5-year OS rates were 92%, 80% and 59%, respectively.)

“Patients who underwent R0 resection had a significantly better median OS from initial diagnosis compared with those who underwent R1/R2 resection and those who were conservatively treated” (97 vs. 89 vs. 36 months, respectively; P= 0.0001), they reported.

Multivariate analysis identified several independent correlates of OS: presence of bilobar metastases (hazard ratio [HR] = 2.724, 95% CI: 1.378-5.383; P = 0.004); PNEC-G3 (HR=6.138; 95% CI: 2.816-13.378; P = 0.0001); and R0 resection (HR = 0.446; 95% CI: 0.268-0.741; P = 0.002).