Gonadal function and fertility after stem cell transplantation in childhood: comparison of a reduced intensity conditioning regimen containing melphalan with a myeloablative regimen containing busulfan

<jats:title>Summary</jats:title><jats:p>The occurrence of late sequelae after myeloablative conditioning regimens for stem‐cell transplantation (<jats:styled-content style="fixed-case">SCT</jats:styled-content>) has prompted the introduction of reduced‐intensity chemotherapy (<jats:styled-content style="fixed-case">RIC</jats:styled-content>) regimens in an attempt to reduce toxicity and spare fertility. We retrospectively evaluated gonadal function in survivors of <jats:styled-content style="fixed-case">SCT</jats:styled-content> in childhood by comparing patients conditioned with a myeloablative regimen containing busulfan and cyclophosphamide (BuCy, <jats:italic>N</jats:italic> = 51, 28 boys) and a <jats:styled-content style="fixed-case">RIC</jats:styled-content> regimen containing fludarabine and melphalan (FluMel, <jats:italic>N</jats:italic> = 40, 19 boys). Spontaneous puberty occurred in 56% of girls and 89% of boys after BuCy, whereas 90% of females and all males in the FluMel group entered puberty spontaneously (<jats:italic>P</jats:italic> = 0·012). Significantly more females (61%) conditioned with BuCy required hormone replacement compared with the FluMel group (10·5%, <jats:italic>P</jats:italic> = 0·012). Females in the FluMel group took significantly longer to develop elevation of serum follicle‐stimulating hormone (<jats:styled-content style="fixed-case">FSH</jats:styled-content>) concentrations (>10 iu/l) from the onset of puberty than females in the BuCy group (median 5·2 years vs. 2·7 years respectively, <jats:italic>P</jats:italic> = 0·0135). In males no difference was noted between the two conditioning groups in time to <jats:styled-content style="fixed-case">FSH</jats:styled-content> elevation (median 4 years in FluMel <jats:italic>versus</jats:italic> 6 years in BuCy). Whilst the two regimens have similar effects on the testis, ovarian function seems to be better preserved in females undergoing <jats:styled-content style="fixed-case">SCT</jats:styled-content> with <jats:styled-content style="fixed-case">RIC</jats:styled-content>.</jats:p>