AB017. SOH22ABS100. Post-treatment surveillance for low-grade appendiceal mucinous neoplasms (LAMN): results from a national surveillance programme
Colorectal Session

AB017. SOH22ABS100. Post-treatment surveillance for low-grade appendiceal mucinous neoplasms (LAMN): results from a national surveillance programme

Lukas O’Brien1, Enda Hannan1, Lorena Martin Roman1, Anna Mueller1, John Aird2, Conor Shields1, Jurgen Mulsow1

1The National Centre for Peritoneal Malignancy, Mater Misericordiae University Hospital, Dublin, Ireland; 2Department of Histopathology, Mater Misericordiae University Hospital, Dublin, Ireland

Background: Low-grade appendiceal mucinous neoplasm (LAMN) is an unusual tumour that can progress to pseudomyxoma peritonei (PMP). There is a lack of standardisation of surveillance for LAMN as the progression rate is unclear. The purpose of this study was to evaluate the rate of progression of LAMN to PMP in a national surveillance programme.

Methods: Data for all patients referred for LAMN surveillance from 2014 to 2020 was retrospectively collected. The surveillance regime consisted of annual computed tomography and tumour markers for a five-year period. Patients that progressed to PMP were identified.

Results: Of 65 patients with LAMN enrolled in the programme, 54 had completed at least one year of surveillance (66.7% female, median age 49 years). Of these, 11.1% (n=6) progressed to PMP. The median time to progression was 24 months (range, 13–24 months). In those that progressed, resection margins were positive in 33.3% (n=2), T staging was T4a in 83.3% (n=5), tumour markers were elevated in 50% (n=3). All remaining patients were disease free at a median follow-up of 36 months (range, 12–84 months). In those that did not progress, 1 patient (2.1%) had positive margins (P<0.001), 2 (4.2%) had elevated tumour markers (P<0.001) and 50% (n=24) had T4a disease (P=0.06).

Conclusions: Our findings suggest that, while LAMN has a relatively low risk of progression to PMP, the current surveillance regime is justified, with progression being highest within the first two years of diagnosis. Positive resection margins and elevated tumour markers appear to confer a higher progression risk.

Keywords: Appendiceal tumour; low-grade appendiceal mucinous neoplasm (LAMN); peritoneal malignancy; pseudomyxoma peritonei (PMP)

Acknowledgments

Funding: None.

Footnote

Conflicts of Interest: The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

doi: 10.21037/map-22-ab017
Cite this abstract as: O’Brien L, Hannan E, Roman LM, Mueller A, Aird J, Shields C, Mulsow J. AB017. SOH22ABS100. Post-treatment surveillance for low-grade appendiceal mucinous neoplasms (LAMN): results from a national surveillance programme. Mesentery Peritoneum 2022;6:AB017.

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