Gastroenteropancreatic NETs Show Late Recurrence Patterns

Follow-up imaging for gastroenteropancreatic neuroendocrine tumours could be optimised to match later patterns of recurrence

medwireNews: A delayed pattern of gastroenteropancreatic neuroendocrine tumour (GEP–NET) recurrence has been uncovered, say researchers who believe this could be used to improve the timing of follow-up imaging.

“Disease recurrence occurs much later than most other gastrointestinal tract cancers”, report Simron Singh, from Sunnybrook Health Sciences Centre in Toronto, Ontario, Canada, and colleagues.

The team collated data for 936 GEP–NET patients, aged a median of 60 years at diagnosis, who first underwent resection in Canada between 1994 and 2012.

The most common tumour site was the small intestine (46.6%), while pancreatic NETs occurred in 20.0% of the cohort, the investigators explain in a research letter published in JAMA Oncology.

After a median follow-up of 46.8 months, the overall survival (OS) rate of the whole population was determined at 3, 5, 10 and 15 years to be 92.2%, 85.4%, 68.1% and 54.6%, respectively. 

However, the researchers note there was significant variation in survival by site. In particular, patients with small intestine NETs had similar OS to pancreatic NET patients at 3 years (93.7 vs 95.6%) but poorer OS after 10 years (66.9 vs 74.2%) and 15 years (49.1 vs 68.1%).

After 3 years, just 23.3% of patients in the overall population had experienced recurrence, rising to 33.5% at 5 years, 48.5% at 10 years and 58.3% at 15 years, the investigators say. And patients with pancreatic NETs experienced recurrence significantly earlier than the whole study group, with corresponding rates of 26.5%, 39.6%, 57.0% and 69.4%.

This contrasted with the use of imaging surveillance, which declined significantly over time, from a rate of 1.04 investigations per 100 patient–days in the first 3 months of follow-up to 0.29 investigations in months 25–36 and 0.18 investigations from months 109–120. 

“The observed patterns of imaging are incongruent with the observed timeframe of recurrence, particularly in the first 3 years where only one third of cancers recur”, Simron Singh et al comment.

Acknowledging that their analyses “are limited by the lack of detailed pathologic data, particularly Ki-67 index and lymph node status”, the authors recommend: “Future research should focus on the cost-effectiveness of surveillance and its impact on patient outcomes.

“These data can inform guidelines for surveillance in this population that accounts for the natural history of this disease”, they suggest.



Singh S, Chan DL, Moody L, et al. Recurrence in resected gastroenteropancreatic neuroendocrine tumors . JAMA Oncol; Advance online publication 15 March 2018.

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