Study reveals wealth of information on appendiceal neuroendocrine tumors

By Liz Meszaros, MDLinx
Published October 24, 2017

Key Takeaways

In patients with appendiceal neuroendocrine tumors, 10 mm may be a more accurate cutoff for predicting lymph node (LN) metastasis, according to researchers here at the North American Neuroendocrine Tumor Society (NANETS) 2017 Symposium, held in Philadelphia, PA, October 19-21.

They also found that in patients with well-differentiated neuroendocrine tumors (WDNETs) and nodal involvement, prognosis is excellent, and subsequent right hemicolectomy (RHC) may not be necessary in selected patients with competing comorbidities. Finally, in patients with mixed histology tumors (MHTs) with LN metastases, survival is poor despite RHC, and clinicians should assess the possible role of adjuvant therapy, they concluded.

“What we noticed in clinical practice is that patients often present with symptoms concerning for appendicitis. They undergo surgery with appendectomy. We find that a proportion of these patients have incidentally diagnosed tumors that were not picked up before the surgery. The most common type of such tumors noted in the appendix after appendectomy are neuroendocrine tumors,” explained senior author Arvind Dasari, MD, assistant professor, Medical Oncology, Department of Gastrointestinal Medical Oncology, University of Texas MD Anderson Cancer Center, Houston, TX.

“The questions that come up after the initial appendectomy are ‘Does the patient need additional surgery after the appendectomy? and ‘How will that impact patient survival?’ These are questions that are unanswered and we aim to try to answer these questions through our study,” he added.

For this study, Dr. Dasari and colleagues used the SEER database to identify 1,731 patients diagnosed with appendiceal tumors between 1988 and 2012.

In all, 38.0% had WDNETs with a 10-year cancer specific survival (CSS) of 92.6%, 60.8% had MHTs with a 10-year CSS of 78.1%, and 1.2% had poorly-differentiated neuroendocrine carcinomas (PDNECs) with a 10-year CSS of 0%.

Among all patients, 19.2% had lymph node involvement. In those with WDNETs who had adequate lymph node dissection, which researchers defined as examination of greater than or equal to 12 LNs, researchers found higher rates of LN involvement for tumors that were 11-20 mm in size compared to those that were less than 10 mm (56.8% vs 11.6%, P < 0.001).

Similarly, in subjects with MHTs who underwent adequate lymph node dissection, they found higher rates of LN involvement for tumors 11-20 mm compared with those less than or equal to 10 mm (32.9% vs 10.4%, respectively; P=0.004).

In patients with no distant metastasis, CSS analysis revealed that the only significant characteristics were histologic type, age of greater than 65 years at the time of diagnosis, and lymph node involvement. In subjects with regionally advanced MHTs, the type of surgery, RHC vs simple appendectomy, had no effects on survival (HR: 1.00; 95% CI: 0.53, 1.89; P=0.99).

Finally, in patients with regionally advanced WDNET, researchers observed excellent prognosis, regardless of which type of surgery they underwent, and only 3 of 188 died from cancer within 10 years.

“The take-home message would be, at least for my practice, when you have a patient with well-differentiated neuroendocrine tumor who just had an appendectomy,  and you’re trying to decide whether you should send the patient for a right hemicolectomy, I think you should consider the entire clinical picture,” said Dr. Dasari.

“For instance, if it is a patient with a lot of comorbidities who may be at a high surgical risk, then it may be reasonable not to do the right hemicolectomy, and just monitor the patient because these patients may have a good prognosis. In other patients, I think it should be a consensus decision in consultation with the surgeon,” he concluded.

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