Wide Variation in Follow-Up Practices After Neuroendocrine Tumor Resection

San Francisco, CA—Follow-up for completely resected gastroenteropancreatic neuroendocrine tumors (GEP-NETs) varies widely, and the majority of clinicians ignore existing clinical guidelines, an international survey showed, reported Eva Segelov, MBBS (Hons 1), PhD, FRACP, Associate Professor of Medicine, St Vincent’s Clinic, Sydney, New South Wales, Australia, and colleagues, during a poster presentation at the 2017 Gastrointestinal Cancers Symposium.

Follow-up practices varied according to tumor histology, location of the primary tumor, and the type of surgical procedure, but not by the annual patient volume. Tumor grade and the tumor proliferation marker Ki-67 or mitotic count most often influenced a surgeon’s protocol, but neither factor was cited by the majority of the 163 survey participants.

In addition, the majority of the surgeons acknowledged only minimal or moderate familiarity with existing clinical guidelines, and no more than 27% of the survey respondents found any particular guideline “very useful.” Surgical volume had no obvious influence of follow-up practices, according to this study.

Real-World Practice

A detailed examination of GEP-NETs recurrence involved the Commonwealth Neuroendocrine Tumour (CommNET) collaboration, which is a large NETs database that includes participants from Australia, New Zealand, and Canada.

To investigate real-world follow-up practices after complete resection of GEP-NETs, Dr Segelov and colleagues developed an electronic survey, which they distributed to members of CommNET and the North American Neuroendocrine Tumor Society. The survey addressed respondent demographics, knowledge and use of current guidelines, and follow-up practices.

The investigators received usable responses from 163 members, which formed the basis of the data analysis. Respondents were stratified by country, patient volume, and specialty. Categories of patient volumes included low (0-10 patients yearly), medium (11-50 patients yearly), and high (>50 patients yearly).

Medical oncologists accounted for 50% of the survey respondents, followed by surgeons (23%), nuclear medicine specialists (13%), and others (14%). Dr Segelov and colleagues acknowledged respondents’ interpretation of various terms (eg, “complete resection”) as a potential confounding factor in discussing optimal follow-up of patients after surgical resection of GEP-NETs.

More than 40% of the respondents had annual new patient volumes of 0 to 10 patients (0-4 patients, 16%; 5-10 patients, 26%), followed by 11 to 50 patients (34%), 51 to 100 patients (10%), and >100 patients (13%). Approximately 40% of the total patient volume for follow-up (N = 159) involved respondents with 0 to 10 patients, 36% with 11 to 50 patients, and 21% with ≥51 patients.

Adherence to Follow-Up Guidelines Questioned

Overall, 38% of respondents considered themselves “very familiar” with the National Comprehensive Cancer Network clinical guidelines, followed by the European Neuroendocrine Tumor Society consensus guidelines (33%), and the European Society for Medical Oncology guidelines (17%), but only 15%, 27%, and 10% of respondents found them “very useful,” respectively.

In addition, 63% of respondents did not have institutional guidelines for follow-up after the complete resection of GEP-NETs. Approximately 20% of the respondents reported that they did not follow guidelines, because recommendations were too difficult or impractical, and a similar proportion of respondents said that guidelines were not appropriate for most of their cases. Approximately 70% of respondents reported other reasons for their lack of adherence to follow-up guidelines.

Several published guidelines exist for follow-up after complete resection of GEP-NETs. In general, the guidelines call for closer surveillance of GEP-NETs than surveillance of other gastrointestinal malignancies, particularly during the first 3 years after surgery. Given the different guidelines and their overall complexity, surgeons’ knowledge of and adherence to the guidelines may vary, noted Dr Segelov and colleagues.

NETs comprise a heterogeneous group of cancers, and knowledge of NET recurrence remains poorly documented. Practical, tailored follow-up may be more appropriate than guideline-based follow-up, because clinical guidelines may lead to overinvestigation, associated with more resource-intense evaluations, noted Dr Segelov and colleagues.

Factors Influencing Follow-Up Practices

With regard to factors that influenced follow-up practices for completely resected GEP-NETs, approximately 40% of respondents cited tumor grade and a similar proportion cited Ki-67 values or mitotic count; stage, nodal status, and site of tumor origin had less influence on follow-up practices than tumor grade and Ki-67 values or mitotic count.

The majority of respondents followed patients at 6-month intervals during the first 2 years (62%), every 12 months during years 3 to 5 (59%), and every 12 months thereafter (41%). NET-specific follow-up ended after 5 years for 28% of respondents, after 6 to 10 years for 26% of respondents, and beyond 10 years for 23% of respondents. Patient volume did not influence the duration of follow-up.

However, histology had a substantial impact on follow-up practices. The majority of respondents increased follow-up (ie, frequency of visits or types of testing) for grade 2 versus grade 1 GEP-NETs (51%) and grade 3 versus grade 1 GEP-NETs (90%); for patients with cancerous lymph nodes (53%); and pancreatic versus small bowel primary tumor (40%).

Certain surgical scenarios also influenced follow-up practices; that is, 40% of respondents reported less frequent follow-up for primary appendiceal tumors; 21% of respondents increased follow-up for primary rectal tumors with local excision; and 21% increased follow-up for primary colorectal tumors with surgical resection, including lymph nodes.

The most frequently requested tests for patients with poor prognostic factors included computed tomography scans (66%) and chromogranin A (86%).

Responses did not vary by country, patient volume, or respondent’s specialty.

“This large international survey yielded detailed information about variation in current follow-up practices and raised questions about the applicability of current clinical guidelines,” concluded Dr Segelov and colleagues. “More data regarding patterns and timelines of NET recurrences are needed,” they added.

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