C. Mosquera1, N. Bellamy1, T. L. Fitzgerald1 1East Carolina University Brody School Of Medicine,Division Of Surgical Oncology,Greenville, NC, USA
Introduction: Currently, size is the primary factor utilized to determine risk of regional nodal metastasis for Appendiceal Neuroendocrine Tumors (A-NET). Here we validate a nomogram combining depth of invasion and size to predict risk of nodal disease.
Methods: Patients with resected A-NET from 2004-2013 were identified in the NCDB.
Results: A total of 3,269 patients were included. The majority were female (56.9%), white (88.1%), had no nodal metastasis (74.9%), and received colectomy (61.5%). On univariate analysis, risk of nodal metastasis was associated with greater depth of invasion (LP 13.3%, MP 22.5%, TS 60.0%, p<0.0001), tumor size (<1 cm 3.6%, 1-2 cm 19.8%, 2-4 cm 45.6%, > 4 cm 44.1%, p<0.0001), and extent of surgical resection (appendectomy 12.8%, colectomy 30.0%, p<0.0001). On multivariate analysis depth of invasion (LP vs MP OR 1.03 p=0.8924; LP vs TS OR 4.02, p <0.0001), size (<1 cm vs 1-2 cm OR 5.81, p<0.0001; <1cm vs 2-4 cm OR 16.78, p<0.0001; <1 cm vs >4 cm OR 13.02, p <0.0001), and extent of surgical resection (colectomy vs appendectomy OR 2.09, p<0.0001) continued to be significant. On univariate survival analysis of 5-year DSS, depth of invasion (LP 88.5%, MP 84.8%, TS 58.2%, p<0.0001), size (<1 cm 84.5%, 1-2 cm 86.3%, 2-4 cm 81.5%, >4 cm 75.4%, p=0.0004), and extent of surgical resection (appendectomy 85.3%, colectomy 80.7%, p=0.0006) were predictive of survival. On multivariate survival analysis, increased depth of invasion (LP vs MP HR 1.73 p=0.1709; LP vs TS HR 5.63, p=0.0023) and size (<1 cm vs 1-2 cm HR 0.12, p<0.0001; <1cm vs 2-4 cm HR 0.34, p=0.0129; <1 cm vs >4 cm HR 0.21, p=0.0034) were associated with survival, however, extent of surgical resection was not (colectomy vs appendectomy HR 1.86, p=0.1188). A nomogram was created to assess the risk of nodal metastasis determined by size and depth of invasion (see figure). The model accurately predicts risk of lymph node metastasis for A-NET with an area under the Received Operating Characteristic (ROC) curve of 0.77200. In order to eliminate bias of low lymph node retrieval with only appendectomy, a model including only colectomy patients was constructed. All results were similar with the ROC of 0.75301.
Conclusion: This study validates the utility of a nomogram including depth of invasion and size to predict risk of nodal metastasis of A-NET. Given that depth predicts both risk of lymph node metastasis and mortality, consideration should be given to including this data in AJCC T classification.
