O-262 Impact of the cancer treatment received on the quality of the human (pre)pubertal testicular tissue prior to testicular tissue freezing (TTF)

Abstract Study question What is the impact of the cancer treatment received prior to TTF and the disease on spermatogonia quantity in testicular tissue from (pre)pubertal boys? Summary answer A decrease in spermatogonia number was observed in testicular tissue after cancer treatment when cyclophosphamide equivalente dose (CED) is above 4000 mg/m2. What is known already The improved survival rates associated with the development of sperm and testicular tissue freezing (TTF) renders difficult not to offer fertility preservation to children or adolescents before cancer. Several studies exploring cancer patients have examined the number of spermatogonia per seminiferous tubular cross-section (S/T) or tubular fertility index (TFI, percentage of tubular cross-sections containing spermatogonia) in testicular biopsies. All studies, demonstrated that the S/T and TFI always decreased after the introduction of chemotherapy and more specifically in case of highly gonadotoxic risk such as alkylating agents. Study design, size, duration Testicular tissue samples from 79 (pre)pubertal boys diagnosed with cancer (ranging from 6 month to 16 years of age) were cryopreserved between May 2009 and June 2014. Medical diagnosis and previous chemotherapy exposure were recorded. We examined histological sections of (pre)pubertal testicular tissue to elucidate whether chemotherapy, doses or primary diagnosis affects the quality of testicular tissue. Participants/materials, setting, methods (Pre)pubertal boys with cancer diagnosis who benefitted from TTF prior to conditioning treatment for hematopoietic stem cell transplantation. All the patients included had previously received chemotherapy with moderate risk for future fertility. We have selected patients for whom data on chemotherapy received were complete. The quantity of spermatogonia and quality of testicular tissue were assessed by both morphological and immunohistochemical analysis. Main results and the role of chance The main finding was a significant reduction in spermatogonial cell counts in boys treated with alkylating agents. The mean S/T values in boys exposed to alkylating agents was significantly lower than in a group exposed to non-alkylating agents (p = 0.018). In contrast, no difference was observed for patients treated with carboplatin as the only alkylating agent compared to the group of patients exposed to non-alkylating agents. We observed an increase of S/T with age in the group of patients who did not receiv