What should be done in terms of fertility preservation for patients with cancer? The French 2021 guidelines

International audienceAbstract Aim: To provide practice guidelines about fertility preservation (FP) in oncology. 93Methods: We selected 400 articles after a PubMed review of the literature (1987e2019). Recommendations: Any child, adolescent and adult of reproductive age should be informed about the risk of treatment gonadotoxicity. In women, systematically proposed FP counselling between 15 and 38 years of age in case of treatment including bifunctional alkylating agents, above 6 g/m2 cyclophosphamide equivalent dose (CED), and for radiation doses on the ovaries 3 Gy. For postmenarchal patients, oocyte cryopreservation after ovarian stimulation is the firstline FP technique. Ovarian tissue cryopreservation should be discussed as a first-line approach in case of treatment with a high gonadotoxic risk, when chemotherapy has already started and in urgent cases. Ovarian transposition is to be discussed prior to pelvic radiotherapy involving a high risk of premature ovarian failure. For prepubertal girls, ovarian tissue cryopreservation should be proposed in the case of treatment with a high gonadotoxic risk. In pubertal males, sperm cryopreservation must be systematically offered to any male who isto undergo cancer treatment, regardless of toxicity. Testicular tissue cryopreservation must be proposed in males unable to cryopreserve sperm who are to undergo a treatment with intermediate or severe risk of gonadotoxicity. In prepubertal boys, testicular tissue preservation is: - recommended for chemotherapy with a CED 7500 mg/m2 or radiotherapy 3 Gy on both testicles. - proposed for chemotherapy with a CED 5.000 mg/m2 or radiotherapy 2 Gy. If several possible strategies, the ultimate choice is made by the patient