Abstract
Background
This is the first report from a multicenter prospective cohort study of colorectal neuroendocrine tumor (NET), the C-NET STUDY, conducted to assess the long-term outcomes of the enrolled patients. This report aimed to elucidate the clinicopathological features of the enrolled patients and lesions.
Methods
Colorectal NET patients aged 20–74 years were consecutively enrolled and followed up at 50 institutions. The baseline characteristics and clinicopathological findings at enrollment and treatment were assessed.
Results
A total of 495 patients with 500 colorectal NETs were included. The median patient age was 54 years, and 85.3% were asymptomatic. The most frequent lesion location was the lower rectum (88.0%); 99.4% of the lesions were clinically diagnosed to be devoid of metastatic findings, and 95.4% were treated with endoscopic resection. Lesions < 10 mm comprised 87.0% of the total, 96.6% had not invaded the muscularis propria, and 92.6% were classified as WHO NET grade 1. Positive lymphovascular involvement was found in 29.2% of the lesions. Its prevalence was high even in small NETs with immunohistochemical/special staining for pathological assessment (26.4% and 40.9% in lesions sized < 5 mm and 5–9 mm, respectively). Among 70 patients who underwent radical surgery primarily or secondarily, 18 showed positive lymph node metastasis.
Conclusions
The characteristics of real-world colorectal NET patients and lesions are elucidated. The high positivity of lymphovascular involvement in small NETs highlights the necessity of assessing the clinical significance of positive lymphovascular involvement based on long-term outcomes, which will be examined in later stages of the C-NET STUDY.
Trial registration number
UMIN000025215.
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Acknowledgements
We would like to thank all investigators and physicians who participated in this study at the 50 participating institutions. We are also grateful to Ms. Natsuko Nishida and Ms. Naoko Sawada for their contribution to the study management. We also thank Editage (www.editage.com) for editing the draft of the manuscript.
Funding
This study was supported by the Japan Agency for Medical Research and Development (AMED; JP16ck0106102, JP19ck0106276).
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All authors were involved in the design of the study and the data collection. MS, TM, and HI analyzed the data. MS drafted the article. All authors contributed to the critical revision of the article for important intellectual content and approved the final version of the article.
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The following author disclosed financial relationships: Y. Takeuchi received speaker’s honoraria from Olympus. All other authors disclosed no conflict of interest.
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Sekiguchi, M., Hotta, K., Takeuchi, Y. et al. Characteristics of colorectal neuroendocrine tumors in patients prospectively enrolled in a Japanese multicenter study: a first report from the C-NET STUDY. J Gastroenterol 57, 547–558 (2022). https://doi.org/10.1007/s00535-022-01877-5
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DOI: https://doi.org/10.1007/s00535-022-01877-5