Full Surgical Resection Should Be Performed Whenever Possible for Gastroenteropancreatic NETs

Katherine Van Loon, MD, MPH

Full surgical resection (R0) of gastroenteropancreatic neuroendocrine tumors (NETs) is associated with a greater than 90% survival rate at five years, according to findings presented at the 2015 North American Neuroendocrine Tumor Society (NANETS) symposium. The rate of recurrence varied by tumor location and stage, but the majority of patients with all types of NETs who underwent full resection were still free of recurrence in the five-year time frame.

“The presence of metastatic disease does not seem as though it should deter attempts at R0 resection when it’s feasible,” according to lead author Katherine Van Loon, MD, MPH, a gastrointestinal cancer specialist at the University of California, San Francisco, Medical Center. She noted that there were differences in disease-free survival in patients who had NETs in the pancreas and small bowel depending on their stage at diagnosis, but a significant difference in overall survival was not detected.

Current NCCN guidelines recommend that patients with gastrointestinal NETs undergo complete resection of the primary tumor and metastases whenever possible, but until now, large multicenter studies looking at recurrence rates in patients who undergo this procedure have not be conducted.

The multicenter study reviewed 1125 patients who were treated at seven NCCN institutions between 2004 and 2012. It included patients 18 or older who had a new diagnosis of NET of the small bowel, pancreas, or colon/rectum, and who underwent complete resection for their primary tumor and any metastatic tumors. Of the 1125 total patients in the database diagnosed with GI NETs, 294 underwent R0 resection and were disease-free after surgery. The median follow-up time from surgery was 62.1 months.

The patients included in the analysis were 51% male and 88% Caucasian. The median age of patients in the study was 55 years, with a range from 20 to 90 years. Patients with colon/rectal NETs tended to be younger and healthier than patients with pancreas or small bowel tumors, Van Loon said.

Among patients with pancreatic NETs, 26% recurred. For patients with small bowel NETs, 18% recurred. For patients with colorectal NETs, 11% recurred. The overall recurrence rate was 21% (n = 61).

Van Loon noted in her presentation that for patients who were followed longer than the median of about five years, recurrences continued to happen after that five-year time point. She pointed out that NCCN guidelines recommend follow-up scans by multiphase CT and/or MRI every 6-12 months for up to ten years, but these guidelines are “notably, very vague.”

She also said that it’s “significant to note that close to 40% of patients in the first year following surgery underwent no imaging,” despite the fact that NCCN guidelines recommend that scans be performed 3-12 months after surgery.

“Surveillance practices were variable, suggesting a need for refinement of the guidelines,” Van Loon said.

The study also looked at the sites of recurrence for the 61 patients who had recurrences.

“The majority of recurrences that were reported were liver recurrences,” Van Loon said, but data were missing on the location of recurrence in many patients, resulting in one of the study’s limitations.

One notable finding was that only one patient had a recurrence in the lung.

“Thus, I would say that chest imaging as part of routine surveillance following R0 resection may be of limited utility,” she said.

Current NCCN guidelines do not include chest imaging, but the researchers wanted to investigate that recommendation.

Regarding future direction, Van Loon recommended that there be more inquiry into frequency, type, and location of recurrence following surgery. She also said that future research should follow patients for longer than five years, because studies have shown that liver recurrences can appear up to ten years later. That was not possible in the current study because the database was closed in 2012.

Van Loon K, Zhang L, Creasman J, et al. Recurrence Patterns Following Surgical Resection of Gastroenteropancreatic Neuroendocrine Tumors: An Analysis from the NCCN Oncology Outcomes Database. Presented at: 2015 NANETS Symposium; October 15-17; Austin, TX. Abstract C42.

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