A 10-year experience in testicular tissue cryopreservation for boys under 18 years of age: What can be learned from 350 cases?

BACKGROUND: A growing number of centers worldwide are preserving testicular tissue (TT) of young boys at risk of fertility loss to preserve their fertility. Data in this regard are scarce and experience sharing is essential to the optimization of the process. OBJECTIVES: This report of our 10-year activity of pediatric fertility preservation (FP) has the objective to (1) improve knowledge regarding the feasibility, acceptability, safety, and potential usefulness of the procedure; (2) analyze the impact of chemotherapy on spermatogonia in the cryopreserved TT. MATERIALS AND METHODS: For this retrospective study of data prospectively recorded, we included all boys under 18 years of age referred to the FP consultation of our academic network between October 2009 and December 2019. Characteristics of patients and cryopreservation of testicular tissue (CTT) were extracted from the clinical database. Univariate and multivariate analyses were used to assess factors associated with the risk of absence of spermatogonia in the TT. RESULTS: Three hundred and sixty-nine patients (7.2 years; 0.5-17.0) were referred to the FP consultation for malignant (70%) or non-malignant (30%) disease, of whom 88% were candidates for CTT, after a previous chemotherapy exposure (78%). The rate of recorded immediate adverse events was 3.5%, with painful episodes dominating. Spermatogonia were detected in the majority of TTs: 91.1% of those exposed to chemotherapy and 92.3% of those not exposed (p = 0.962). In multivariate analysis, the risk of absence of spermatogonia was almost three-fold higher in boys > 10 years of age ([OR] 2.74, 95% CI 1.09-7.26, p = 0.035) and four-fold higher in boys exposed to alkylating agents prior to CTT ([OR] 4.09, 95% CI 1.32-17.94, p = 0.028). DISCUSSION/CONCLUSION: This large series of pediatric FP shows that this procedure is well accepted, feasible, and safe in the short term, strengthening its place in the clinical care pathway of young patients requiring a highly gonadotoxic treatment. Our results demonstrate that CTT post-chemotherapy does not impair the chance to preserve spermatogonia in the TT except when the treatment includes alkylating agents. More data on post-CTT follow-up are still required to ensure the long-term safety and usefulness of the procedure.

Factors associated with the collection of isolated immature oocytes during ovarian tissue cryopreservation.

PURPOSE: To identify patient characteristics associated with successful isolated immature oocyte retrieval (IsO) during ovarian tissue cryopreservation (OTC) and to determine whether they are predictive of the collection of larger numbers of oocytes. METHODS: We retrospectively analyzed all patients undergoing OTC with IsO for fertility preservation over three years of activity at a university hospital. Univariate and multivariate analyses were used to identify the patients with the highest and lowest chances of oocyte recovery, and those with the largest numbers of oocytes. We also analyzed the correlation of IsO with the number of ovarian fragments collected and histological parameters. RESULTS: We analyzed 257 consecutive patients undergoing these procedures, at a median age of 17.1 years [0.3-38.3 years]. Isolated oocytes were obtained from 47.1% of patients, and IsO was more likely in patients with ovulatory cycles (63.0% vs. 38.6%; P≤ .001), without chemotherapy before OTC (61.4% vs. 33.1; P< .001) and with non-malignant diseases other than Turner syndrome (77.5%). Oocyte collection failure rates were highest in patients with Turner syndrome (OR 25.0, 95% CI 3.99-157.0; P< .001) or undergoing chemotherapy with alkylating agents before OTC (OR 37.6, 95% CI 8.36-168.8; P< .001). Prepubescent status (P= .043) and large numbers of ovarian fragments (P< .001) were associated with the retrieval of larger numbers of oocytes. Oocyte recovery was correlated with the presence of follicles in the medulla, but not with follicular density. CONCLUSION: The chances of IsO differ between patients. Identifying patients with the highest chances of success facilitates appropriate resource allocation.

[Fertility preservation for children and adolescents before gonadotoxic treatment]. / Préservation de la fertilité des enfants et adolescents avant un traitement gonadotoxique.

Gonadotoxic therapies during childhood may impair future fertility in adult life and fertility preservation techniques should be discussed before starting gonadotoxic therapies. In both sexes, fertility preservation means immature gametes cryopreservation. For girls, ovarian tissue cryopreservation is the only existing option to preserve fertility in prepubertal girls at risk of premature ovarian failure. This promising approach involves the storage of a large number of follicles, which could subsequently be transplanted or cultured to obtain mature oocytes. For boys, spermatogonial stem cells can be cryopreserved and testicular pieces can be stored for future use. For prepubertal boys it is still an experimental procedure. Animal data reveals that healthy offspring were obtained after grafting of frozen spermatogonia and after in vitro maturation.

[Fertility and cancer]. / Fertilité et cancer.

Information about chemo and/or radiotherapy gonadotoxicity and about fertility preservation is essential. Sperm cryopreservation has to be systematically offered before gonadotoxic treatments. Efficiency of ovarian function preservation with GnRH agonists is still debated. A controlled ovarian stimulation is necessary before oocyte or embryo cryopreservation. It is only feasible if the treatment is not urgent and if the tumor is not hormone-sensitive. If the treatment is highly gonadotoxic, an ovarian tissue cryopreservation may be appropriate. It is the only fertility preservation technique feasible for prepubertal girls. It is now possible to preserve the fertility of prepubertal boys by cryopreservation of testicular tissue. It is essential to send patients and/or their parents to a specialized fertility preservation center.