Natural course of an untreated metastatic perirectal lymph node after the endoscopic resection of a rectal neuroendocrine tumor

Tumor grade 2 as the independent predictor for lymph node metastasis in 10-20 mm sized rectal neuroendocrine tumor

Purpose

Rectal neuroendocrine tumors (NETs) <10 mm are endoscopically resected, while those ≥20 mm are treated with radical surgical resection. The choice of treatment for 10-20 mm sized rectal NETs remains controversial. This study aimed to verify factors predicting lymph node metastasis (LNM) of 10-20 mm sized rectal NET and utilize them to decide upon the treatment strategy.

Methods

Twenty-eight patients with 10-20 mm sized rectal NETs treated at Pusan National University Yangsan Hospital from January 2009 to September 2020 were divided into LNM (+) and LNM (-) groups, and their respective data were analyzed.

Results

Seven patients (25%) had LNM while 21 patients (75%) did not. Endorectal ultrasound findings showed tumor size was significantly larger in the LNM (+) than in the LNM (-) group (15 mm vs. 10 mm, P=0.018); however, pathologically, there was no significant difference in tumor size (13 mm vs. 11 mm, P=0.109). The mitotic count (P=0.011), Ki-67 index (P=0.008), and proportion of tumor grade 2 patients (5 cases, 71% vs. 1 case, 5%; P=0.001) were significantly higher in the LNM (+) group. In multivariate analysis, tumor grade 2 was the independent factor predicting LNM (odds ratio, 61.32; 95% confidence interval, 3.17-1,188.64; P=0.010).

Conclusion

Tumor grade 2 was the independent factor predicting LNM in 10-20 mm sized rectal NETs. Therefore, it could be considered as the meaningful factor in determining whether radical resection is necessary.

Lymphovascular invasion as a prognostic value in small rectal neuroendocrine tumor treated by local excision: A systematic review and meta-analysis

Because rectal neuroendocrine tumors (NETs) are usually small-sized despite of malignant potential, endoscopic resection techniques are recommended. It is unclear whether the lymphovascular invasion (LVI) in the endoscopic resected specimens of small rectal NETs should be indicated for completion surgery. We performed a systematic review and meta-analysis for the incidence of LVI in small rectal NETs (≤20 mm) treated by endoscopic resection and its prognostic impacts. We searched the relevant literature published before January 2019. A total of 21 publications including 1816 patients were enrolled. Overall prevalence of LVI in small rectal NETs was 21.8%. Immunohistochemical method significantly increased the detection rate of LVI up to 35.8% compared than H&E staining only (13.2%). Tumor size more than 5 mm was a risk factor for LVI in small rectal NET, whereas tumor grade did not influence the risk. The LVI in the endoscopic resected specimens was a risk factor for subsequent lymph node metastasis. Separately analyzed in detail, the vascular invasion had a stronger impact on lymph node metastasis than the lymphatic invasion. The prognosis of endoscopically treated rectal NET with LVI was excellent with only 0.3% of recurrence rate during the 5-year follow-up period. LVI is highly prevalent and a risk factor for lymph node metastasis in the small rectal NETs. Endoscopically treated small rectal NETs had excellent short-term prognoses despite of LVI. Immediate completion radical surgery is not absolutely necessary for the LVI-positive small rectal NETs. However, long-term follow-up is recommended for any delayed recurrence.

Lymphovascular invasion in more than one-quarter of small rectal neuroendocrine tumors

AIM

To identify the frequency, clinicopathological risk factors, and prognostic significance of lymphovascular invasion (LVI) in endoscopically resected small rectal neuroendocrine tumors (NETs).

METHODS

Between June 2005 and December 2015, 104 cases of endoscopically resected small (≤ 1 cm) rectal NET specimens at Hallym University Sacred Heart Hospital in Korea were retrospectively evaluated. We compared the detected rate of LVI in small rectal NET specimens by two methods: hematoxylin and eosin (H&E) and ancillary immunohistochemical staining (D2-40 and Elastica van Gieson); in addition, LVI detection rate difference between endoscopic procedures were also evaluated. Patient characteristics, prognosis and endoscopic resection results were reviewed by medical charts.

RESULTS

We observed LVI rates of 25.0% and 27.9% through H&E and ancillary immunohistochemical staining. The concordance rate between H&E and ancillary studies was 81.7% for detection of LVI, which showed statistically strong agreement between two methods (κ = 0.531, P < 0.001). Two endoscopic methods were studied, including endoscopic submucosal resection with a ligation device and endoscopic submucosal dissection, and no statistically significant difference in the LVI detection rate was detected between the two (26.3% and 26.8%, P = 0.955). LVI was associated with large tumor size (> 5 mm, P = 0.007), tumor grade 2 (P = 0.006). Among those factors, tumor grade 2 was the only independent predictive factor for the presence of LVI (HR = 4.195, 95%CI: 1.321-12.692, P = 0.015). No recurrence was observed over 28.8 mo regardless of the presence of LVI.

CONCLUSION

LVI may be present in a high percentage of small rectal NETs, which may not be associated with short-term prognosis.

Cap-assisted EMR for rectal neuroendocrine tumors: comparisons with conventional EMR and endoscopic submucosal dissection (with videos)

BACKGROUND AND AIMS

The incidence of rectal neuroendocrine tumors (NETs) is increasing, and most small rectal NETs can be treated endoscopically. Cap-assisted EMR (EMR-C) was suggested as an effective treatment for rectal NETs in a few studies. We aimed to compare the outcomes of conventional EMR, EMR-C, and endoscopic submucosal dissection (ESD) for the treatment of rectal NETs.

METHODS

A total of 138 rectal NETs were treated endoscopically by a single endoscopist at Asan Medical Center. We analyzed 122 rectal NETs that had been removed by using EMR (n = 56), EMR-C (n = 34), or ESD (n = 32).

RESULTS

The histologic complete resection rate was higher in the EMR-C group than in the EMR group (94.1% vs 76.8%, P = .032). Intraprocedural bleeding tended to be more frequent in the EMR-C group than in the EMR group (8.8% vs 0%, P = .051). No differences in the rates of adverse events or histologic complete resections were observed between the EMR-C group and the ESD group for 6-mm to 8-mm NETs; however, the procedure time was significantly shorter in the EMR-C group (3.9 ± 1.1 minutes) than in the ESD group (19.0 ± 12.1 minutes) (P < .001). There was no recurrence in any of the 3 groups.

CONCLUSIONS

EMR-C is the preferable technique for endoscopic resection of small rectal NETs.

Usefulness of endoscopic resection using the band ligation method for rectal neuroendocrine tumors

Background/Aims

Rectal neuroendocrine tumors (NETs) are among the most common of gastrointestinal NETs. Due to recent advances in endoscopy, various methods of complete endoscopic resection have been introduced for small (≤10 mm) rectal NETs. However, there is a debate about the optimal treatment for rectal NETs. In our study, we aimed to evaluate the efficacy and feasibility of endoscopic resection using pneumoband and elastic band (ER-BL) for rectal NETs smaller than 10 mm in diameter.

Methods

A total of 55 patients who were diagnosed with rectal NET from January 2004 to December 2011 at Gil Medical Center were analyzed retrospectively. Sixteen patients underwent ER-BL. For comparison, 39 patients underwent conventional endoscopic mucosal resection (EMR).

Results

There was a markedly lower deep margin positive rate for ER-BL than for conventional EMR (6% [1/16] vs. 46% [18/39], P=0.029). Four patients who underwent conventional EMR experienced perforation or bleeding. However, they recovered within a few days. On the other hand, patients whounderwent endoscopic resection using a pneumoband did not experience any complications. In multivariate analysis, ER-BL (P=0.021) was independently associated with complete resection.

Conclusions

ER-BL is an effective endoscopic treatment with regards to deep margin resection for rectal NET smaller than 10 mm.