Mucinous adenocarcinoma, gastric type of the uterine cervix: clinical features and HER2 amplification

Mucinous adenocarcinoma, gastric type (GAS) is difficult to diagnose and shows poor prognosis. Trastuzumab, an anti-human epidermal growth factor type 2 (HER2) monoclonal antibody, is effective in HER2-positive stomach cancer. The objectives of this study were to identify the clinicopathological characteristics of GAS and to evaluate HER2 expression in GAS. We retrospectively reviewed 322 cervical cancer cases diagnosed at the Kyoto University Hospital from 2010 to 2016. The incidence, clinical factors including age, stage, and lymph node status, tumor markers, immunoreactive expression of MUC6, HIK1083, and HER2, and HER2 amplification were evaluated. Of the 322 cases of cervical cancer, 13 cases of the adenocarcinoma cases were diagnosed as GAS. Watery discharge, lower abdominal pain, CA19-9 elevation, and lymph node metastasis were frequently observed in GAS (p=0.0226, p=0.0400, p=0.0346, and p=0.0274, respectively). Immunohistochemistry showed positive MUC6 status in all 13 cases and positive HIK1083 status in 8 cases. The HER2 expression status was equivocal in six cases by immunohistochemistry and HER2 amplification was identified in one case. GAS exhibits frequent lymph node metastasis and clinical symptoms such as watery discharge and lower abdominal pain, high levels of CA19-9. In addition, some parts of GAS exhibit HER2 amplification.