460. THE ADDITIONAL VALUE OF CERVICAL ULTRASOUND IN THE DETECTION OF CERVICAL LYMPH NODE METASTASES IN PATIENTS WITH ESOPHAGEAL CANCER

Abstract Background Esophageal cancer patients with cervical lymph node metastases, staged according to the 8th edition of the American Joint Committee on Cancer (AJCC), are considered to have stage IV disease and are generally not eligible for treatment with curative intent. External cervical ultrasound (US) used to be standard in the diagnostic workup for detection of cervical lymph node metastases in the Netherlands, but is no longer included in the esophageal cancer guideline. This study aimed to assess the additional value of US over 18FDG PET-CT for the detection of cervical lymph node metastases in esophageal cancer patients, to reassure justified removal of cervical US from the guideline. Methods This retrospective cohort study included all esophageal cancer patients referred to or diagnosed in the Amsterdam UMC between January 2014 and January 2021. Radiology and multidisciplinary team meeting reports were reviewed to identify patients with suspected cervical lymph node(s). Primary outcome was detection rate of cervical lymph node metastases on ultrasound and/or 18FDG PET-CT. Golden standard was etiology based on Fine Needle Aspiration (FNA). Results This study included 768 patients, with a median age of 66 years. Patients were predominantly male (75.0%) and the majority had an adenocarcinoma (71.9%). On 18FDG PET-CT, 77 patients had suspected cervical lymph nodes. Of those, 39 proved malignant. Seven malignant lymph nodes were missed on 18FDG PET-CT. 18FDG PET-CT had a positive predictive value (PPV) of 50.6%, a negative predictive value (NPV) of 99.0%, a sensitivity of 84.8% and a specificity of 94.7%. Based on US alone, 134 patients had suspected cervical lymph nodes. Of those, 45 proved malignant. One malignant lymph node was missed on US. US had a PVV of 33.6%, a NPV of 99.8%, a sensitivity of 97.8% and a specificity of 87.7%. In total, suspected cervical lymph nodes were documented in 151 patients (19.7%). FNA was conducted in 134 out of 151 patients. Of those, 46 proved malignant. No major complications after FNA were reported. For 21 patients, this resulted in stage migration and changed policy from curative intent to palliative. Conclusion Standard US increases the number of FNA conducted for benign cervical lymph nodes, as the positive predictive value is low (33.6%). However, it does have an additional value as it identifies 15% of cervical lymph node metastases that were not seen on 18FDG PET-CT.