Natural history of autologous sperm cryostorage

Study question: What is the natural history of elective autologous sperm cryostorage prior to gonadotoxic treatment?

Summary answer: We estimate large sample median times to transfer for use, to the man's death or to discard of sperm, and their determinants, as the key operational outcomes of sperm cryostorage.

What is known already: No large sample studies of the natural history of sperm cryostorage prior to gonadotoxic treatment are reported.

Study design, size, duration: This observational single-centre study covered 45 years of outcomes with a survival analysis for sperm cryostorage prior to scheduled gonadotoxic treatment, and its determinants.

Participants/materials, setting, methods: This study included 3923 men (mean age 30 years) who sought sperm cryostorage for a wide range of cancers and other diseases requiring gonadotoxic treatments.

Main results and the role of chance: The median time to transfer for use (n = 371 men 9%) was 2.4 years (quartiles 1.0, 6.0), the median time to death (n = 553 men, 14%) was 1.7 (0.9, 3.3) years, and the median time to discard (n = 1807 men, 46%) was 7.7 (1.7, 11.1) years. In multivariate Cox model regression, the underlying disease, number of storage visits and follow-up visits, and whether sperm were seen at follow-up visits were consistent predictors of times to outcomes.

Limitations, reasons for caution: This study did not investigate sperm cryostorage for reasons other than gonadotoxic treatment, nor the fertilization outcomes of the cryostored sperm.

Wider implications of the findings: These data provide estimates of the key operational factors for sperm cryostorage programs, prior to potentially sterilizing gonadotoxic treatments, and free from financial or insurance restrictions.

Study funding/competing interest(s): There was no specific funding for this study. D.J.H. has provided expert witness testimony to antidoping and professional standards tribunals and is supported by an NHMRC Investigator Grant. The other authors have no disclosures.

Trial registration number: N/A.