Is inhibin B a potential marker of gonadotoxicity in prepubertal children treated for cancer?

BACKGROUND AND OBJECTIVE Chemotherapy treatment of childhood cancer may impair gonadal function, which may be manifested only in adulthood as permanent sterility. Detection of gonadal dysfunction in prepubertal children has been hampered by the absence of a sensitive marker. Inhibin B is secreted by small antral follicles and Sertoli cells in females and males, respectively, and may be a marker of gonadal function in prepubertal children. The aim of this pilot study was to evaluate inhibin B in relation to sensitive measurements of gonadotrophins as markers of the early gonadotoxic effects of chemotherapy in prepubertal children treated for cancer. STUDY DESIGN AND SUBJECTS Twenty-five prepubertal children (9 females), median age 4.5 years (range 1.2-12.8 years) with cancer (16 solid tumours, nine acute lymphoblastic leukaemia, ALL) were studied longitudinally. Blood samples were collected before and during chemotherapy (solid tumours) or immediately following induction and first intensification (ALL). Post-treatment (1-6 months) samples were collected in 12 of the patients (5 females). MEASUREMENTS Dimeric inhibin B was measured by double antibody enzyme-linked immunosorbent assay (ELISA). FSH and LH were measured by sensitive time-resolved immunofluorescence. RESULTS Girls : Pretreatment inhibin B was slightly high in one girl but normal for age and sex in all others: median 16.1 (range 9.4-186.2) ng/l, median SD score +0.2 (-1.3 to +2.6). Inhibin B decreased to undetectable levels (<8 ng/l) in 8/9 girls during treatment (P = 0.03), with no accompanying rise in FSH or LH. Post-treatment recovery of inhibin B was variable: median 16.1 (range < 8.0-44.2) ng/l, median SD score +0.1 (range < -2.4 to +1.8). Sustained undetectable inhibin B levels were observed in 2/5 girls with correspondingly elevated FSH concentrations (11.8 and 10.9 U/l). Boys : Inhibin B was normal for age and sex in all boys before treatment with no significant change during or after treatment (medians 93 ng/l, 85 ng/l and 94 ng/l, SD scores -0.3, -0.6 and -0.2, respectively). Inhibin B decreased to undetectable levels in one boy post-treatment with no accompanying increase in FSH or LH. CONCLUSIONS In prepubertal girls with cancer, chemotherapy is associated with suppression of inhibin B, usually transient, which may indicate arrest of follicle development. Sustained suppression of inhibin B following treatment may be indicative of permanent ovarian damage. In prepubertal boys, chemotherapy had little immediate effect on Sertoli cell production of inhibin B, although one boy showed a delayed effect. Inhibin B, together with sensitive measurements of FSH, may be a potential marker of the gonadotoxic effects of chemotherapy in prepubertal children with cancer.