Assessment of ovarian cortex follicles in chemotherapy naïve and chemotherapy exposed patients.

Background: Histological evaluation of ovarian tissue harvested as part of the attempt to preserve fertility might clarify the mechanism by which ovarian failure is caused. The purpose of this study was to compare the histologic appearance of ovarian tissue harvested for ovarian tissue cryopreservation (OTC) in chemotherapy naïve and chemotherapy exposed patients regarding the presence of follicles in different stages of development and to explore ovarian tissue histology in patients exposed to low- and high-cytotoxicity risk chemotherapy.

Methods: A cohort of post-pubertal cancer survivors who underwent OTC between 1997 and 2018 was evaluated. An expert pathologist reviewed the pathology slides taken during OTC. The assessment included counting number of primordial, primary, secondary, and antral follicles. A comparison was made between chemotherapy naïve and chemotherapy exposed women and further between women who previously received low- versus high-risk gonadotoxic regimens.

Results: Seventy post-pubertal patients were included in the study. Seventeen (24.3%) received chemotherapy prior to OTC, and 53 (75.7%) were chemotherapy naïve at the time of OTC. A significant difference was found only in the number of secondary follicles, which was increased in chemotherapy naïve patients (2.81±4.26 vs. 0.88±1.18, respectively; P=0.005). Similar results were observed in a subgroup analysis of hematologic malignancies separately. Comparison of patients with previous exposure to chemotherapy revealed similar follicular appearance, except for the number of secondary follicles, which was higher in patients receiving low-risk compared to high-risk chemotherapy (1.40±1.28 vs. 0.14±0.35, respectively; P=0.006).

Conclusions: The ovarian follicular pool at OTC appears comparable between chemotherapy naïve individuals and those post-exposure, as well as among patients receiving low versus high-risk gonadotoxic regimens, with the exception of secondary follicles, which are presented in increased numbers in chemotherapy naïve and those exposed to low-risk gonadotoxic chemotherapy.