PP.57 Fetal Microchimerism Does Not Appear to Be Implicated in Epithelial Ovarian Cancer

Abstract

Objective Ovarian cancer is the second most common gynaecologic cancer, and epithelial ovarian tumours are the most common malignant ovarian tumours. Pregnancy is an important factor in risk reduction and improved survival in epithelial ovarian cancers. Persistence of fetal cells after pregnancy, or fetal microchimerism, has been implicated in some female malignancies such as cervical and breast with different hypothesised roles. In this retrospective study, we aimed to determine if fetal microchimeric cells were involved in the progression of ovarian cancer. Study design We investigated a well-characterised archive of epithelial ovarian tumour paraffin-embedded tissue sections from nulliparous and parous women. Fluorescence in situ hybridisation (FISH) was performed to detect male presumed-fetal cells. The outcome of blinded FISH analysis was correlated with reproductive history and clinic-pathological features of the cohort. Results Fetal microchimeric cells were not detected in archived ovarian tumour formalin-fixed and paraffin-embedded tissue sections from parous women. Male-presumed fetal cells were instead found in sections from two nulliparous women, one of who had a previous miscarriage. Tumour cells were found to have multiple copies of X chromosomes by FISH analysis, and some tumour cells had loss of X chromosome relative to the ploidy level. Conclusion These findings imply that fetal microchimerism does not have a significant role in the progression of ovarian cancer. Instead, fetal microchimerism could have a role in preventing the development of ovarian cancer by sensitising the maternal immune system to develop adaptive immunity against tumour cells that express onco-fetal antigens.