Introduction/Background The RACE study is a retrospective cohort study initiated in 2021 involving 61 centres from 13 countries within CEEGOG. Data on rare types of cervical tumours are systematically collected including epithelial, mesenchymal, mixed, melanocytic, lymphoid and haematopoietic, germ-cell, and secondary ones. We present preliminary data regarding the unusual types of cervical adenocarcinomas.

Methodology Inclusion criteria for this analysis were histologically verified adenocarcinomas (unusual types of mucinous adenocarcinomas: intestinal, signet ring, minimal deviation, villoglandular; endometrioid; clear cell; serous; and mesonephric adenocarcinomas) with the date of primary diagnosis between January 2005 and June 2023. Exclusion criteria were histologically proven usual type HPV associated adenocarcinomas (not otherwise specified or mucinous endocervical). The histopathological assessment was performed by local dedicated pathologists.

Results Among 275 rare cervical tumours included in the RACE study so far, 114 (41.5%) were unusual types of cervical adenocarcinomas. Among these, we observed 33 cases of unusual mucinous adenocarcinomas (28.9%), 51 endometrioid adenocarcinomas (44.7%), 25 clear cell adenocarcinomas (21.9%), 2 serous adenocarcinomas (1.8%) and 3 mesonephric adenocarcinomas (2.6%). Unusual types of mucinous adenocarcinomas had shorter estimated median PFS (62m) compared to endometrioid (117m) or clear cell adenocarcinomas (131m), but the differences among the histology types were not statistically significant (PFS p=0.437; OS p=0.645). However, the data for survival analysis are not yet mature enough to achieve reliable outcomes. Estimated median PFS and OS for the most frequent rare cervical adenocarcinomas are presented in table 1.

Conclusion Endometrioid adenocarcinomas were the most common rare cervical adenocarcinomas. Survival analysis showed no significant differences in PFS and OS among the different histological types of unusual adenocarcinomas, but it is affected by the limited sample size and data prematurity. The collection of data within the RACE study and establishing an international multicentre registry is ongoing and outcomes of other analyses will be shared.

Disclosures The authors declare no conflict of interests.