Importance: Primary tumor resection and mesenteric lymph node dissection in asymptomatic patients with stage IV Small Intestinal Neuroendocrine Tumors (SI-NETs) is controversial.
Objective: To determine whether locoregional surgery performed at diagnosis in asymptomatic SI-NETs patients with distant metastases affects overall survival (OS), morbidity and mortality, length of hospital stay (LOS) and re-operation rates.
Design: This investigation was a cohort study of asymptomatic patients with stage IV SI-NET, diagnosed between 1985 and 2015, using the prospective Uppsala database of SI-NETs and the Swedish National Patient Register. Patients included were followed until May 2016 and divided to a first group, which underwent Prophylactic Upfront Surgery within six months from diagnosis Combined with Oncological treatment (PUSCO group) and a second group, which was either treated non-surgically or operated later (Delayed Surgery As Needed Combined with Oncological treatment [DSANCO group]).
Setting: A tertiary referral center with follow-up data from the Swedish National Patient Register.
Participants: We included 363 stage IV SI-NET patients without any abdominal symptoms within 6 months from diagnosis, treated either with PUSCO (n=161) or DSANCO (n=202).
Exposure: PUSCO vs DSANCO.
Main Outcomes and Measures: Overall survival (OS), length of hospital stay (LOS), postoperative morbidity and mortality and re-operation rates measured from baseline. Propensity score match was performed between the two groups.
Results: Two isonumerical groups (n=91) occurred after propensity score matching. There was no difference between groups in OS (PUSCO median 7.9 vs DSANCO 7.6 years; [hazard ratio] HR, 0.98; [95% CI, 0.70-1.37]; log-rank P=.93) and cancer-specific survival (median 7.7 vs 7.6 years, HR, 0.99; [95%CI, 0.71-1.40]; log-rank P=.99). There was no difference in 30-day mortality (0% in both matched groups) or postoperative morbidity (2% vs 1%; P>.99), LOS (median 73 vs 76 days; P=.64), LOS due to local tumor-related symptoms (median 7 vs 11.5 days; P=.81) or incisional hernia repairs (4% in both groups; P>.99). Patients from the PUSCO group underwent more re-operative procedures (14%) compared to the DSANCO group (3%) due to intestinal obstruction (P< .001).
Conclusion: Prophylactic upfront locoregional surgery confers no survival advantage in asymptomatic stage IV SI-NET patients. Delayed surgery as needed seems to be comparable in all examined outcomes, whilst offering the advantage of less re-operations for intestinal obstruction. The value of a priori locoregional surgery in the presence of distant metastases is challenged and needs to be elucidated in a randomized controlled study.