Radiotherapy at a young age reduces uterine volume of childhood cancer survivors.

BACKGROUND: In contrast to chemotherapy, previous irradiation of the uterus carries an increased risk of an adverse pregnancy outcome. Conflicting results exist as regards the ability of the uterus to increase in volume following radiotherapy-induced damage. We measured uterine volume in a cohort of childhood cancer survivors, and assessed uterine response to a high-dose estrogen replacement regimen.
METHODS: Uterine volume was assessed by transvaginal sonography in 100 childhood cancer survivors. Three patients with ovarian failure and severely reduced uterine volume following abdominal or pelvic irradiation were treated with percutaneous estradiol 150 microg/24 h for three cycles, and transvaginal uterine sonography was repeated monthly.
RESULTS: Uterine volume was significantly reduced in nulliparous patients who had received direct uterine irradiation (n = 13; median 13 mL, range 1-52 mL) compared with nulliparous patients who had received chemotherapy only (n = 37; 47 mL, 22-88), radiotherapy above the diaphragm (n = 17; 40 mL, 24-61), or radiotherapy below the diaphragm not directly involving the uterus (n = 13; 34 mL, 8-77) (p < 0.02 in all comparisons). Among nulliparous patients a significant correlation was found between age at direct uterine irradiation and uterine volume (r = 0.78, p = 0.002). No significant improvement in uterine volume, endometrial thickness or uterine artery blood flow was observed in three hypogonadal patients in response to high-dose estrogen replacement therapy.
CONCLUSIONS: Our results indicate that cytotoxic treatment in childhood does not affect adult uterine size. In contrast, uterine irradiation at a young age reduces adult uterine volume. The radiotherapy-induced damage is probably irreversible.