Introduction/Background Uterine mesonephric adenocarcinoma (MNAC), very rare neoplasm, is most common in the cervix and less common in the uterine corpus. There are limited reports on MNAC regarding its characteristics, depending on the origin site. However, several pathological studies have recently reported that MNAC in the uterine body (UB-MNAC) has a high tendency to metastasise to distant organs. This study compared the clinical characteristics of MNAC cases to help decide adjuvant therapy.

Methodology We extracted data from the medical records of patients diagnosed with primary uterine MNAC between October 2008 and February 2019 and retrospectively analysed it.

Results There were seven cases of UB-MNAC and five of MNAC in the uterine cervix (UC-MNAC). Detection rate of distant metastasis/local invasion was higher in the UB-MNAC group (5/7 vs. 1/5). Among advanced UB-MNAC cases, the lungs (n=2), pelvic peritoneum (n=2) and ovary (n=1) were the metastasis sites. Among UC-MNAC cases, only pelvic lymph node metastasis was detected. In the UB-MNAC group, six received adjuvant therapy (Combined chemotherapy - radiation therapy (CCRT): two, chemotherapy: four). In the UC-MNAC group, three received adjuvant therapy (CCRT: two, chemotherapy: one). The follow-up period was 2-78 months (median, 24.5 months). Only one case of UB-MNAC showed progression 7 months after CCRT. There were no significant differences in initial CA-125 levels, clinical symptoms and tumour size.

Conclusion Overall survival (OS) or Progression free survival (PFS) application was limited owing to the overall shortage of cases and duration of follow-up observation. It was difficult to determine post-therapy outcome because there were no treatment guidelines that led to adjuvant therapy administration even in early stages. However, recent studies, including this study, showed that UB-MNAC has more aggressive features compared with UC-MNAC from the point of diagnosis. Therefore, we may consider post-surgery treatment more actively in UB-MNAC cases.

Disclosure Nothing to disclose.