Published online Sep 6, 2020. doi: 10.12998/wjcc.v8.i17.3751
Peer-review started: February 29, 2020
First decision: April 2, 2020
Revised: May 9, 2020
Accepted: August 9, 2020
Article in press: August 9, 2020
Published online: September 6, 2020
Processing time: 188 Days and 1.4 Hours
Pancreatic neuroendocrine tumors (PanNETs) are heterogeneous and indolent; systemic therapy is not essential for every patient with metastatic PanNET. The National Comprehensive Cancer Network guidelines state that delaying treatment is an option for PanNET with distant metastasis, if the patient has stable disease. However, specific factors that influence surveillance were not mentioned. In addition, data regarding the period of active surveillance in patients with metastatic PanNET are lacking.
To specifically determine factors influencing active surveillance in patients with liver metastatic nonfunctioning PanNETs (NF-PanNETs).
Seventy-six patients with liver metastatic NF-PanNETs who received active surveillance from a high-volume institution were enrolled. Time to disease progression (TTP) and time to initiation of systemic therapy were determined.
Thirty-one (40.8%) patients had recurrent liver disease after R0 resection; 45 (59.2%) were diagnosed with liver metastasis. The median follow-up period was 42 mo and 90.7% patients were observed to have disease progression. The median TTP (mTTP) was 10 mo. Multivariate analysis showed that the largest axis of the liver metastasis > 5 mm (P = 0.04), non-resection of the primary tumor (P = 0.024), and T3-4 stage (P = 0.028) were associated with a shorter TTP. The mTTP in patients with no risk factors was 24 mo, which was significantly longer than that in patients with one (10 mo) or more (6 mo) risk factors (P < 0.001). A nomogram with three risk factors showed reasonable calibration, with a C-index of 0.603 (95% confidence interval: 0.47-0.74).
Active surveillance may only be safe for metastatic NF-PanNET patients with favorable risk factors, and other patients progressed rapidly without treatment. Further studies with a larger sample size and a control group are needed.
Core tip: Experience in active surveillance of metastatic pancreatic neuroendocrine tumors (PanNETs) is insufficient in clinical practice. This study includes the experience of active surveillance in 76 patients with liver metastatic nonfunctioning PanNETs (NF-PanNETs) over 20 years. We demonstrated that largest axis of the liver metastasis > 5 mm, non-resection of the primary tumor and T3-4 stage are poor prognostic factors and affect the survival of PanNET patients with liver metastasis. Patients with favorable factors had a time to progressive disease of more than two years without systemic treatment. This subset of PanNET patients with liver metastasis should undergo active surveillance.