Predicting age of ovarian failure after radiation to a field that includes the ovaries.

PURPOSE

To predict the age at which ovarian failure is likely to develop after radiation to a field that includes the ovary in women treated for cancer.

METHODS AND MATERIALS

Modern computed tomography radiotherapy planning allows determination of the effective dose of radiation received by the ovaries. Together with our recent assessment of the radiosensitivity of the human oocyte, the effective surviving fraction of primordial oocytes can be determined and the age of ovarian failure, with 95% confidence limits, predicted for any given dose of radiotherapy.

RESULTS

The effective sterilizing dose (ESD: dose of fractionated radiotherapy [Gy] at which premature ovarian failure occurs immediately after treatment in 97.5% of patients) decreases with increasing age at treatment. ESD at birth is 20.3 Gy; at 10 years 18.4 Gy, at 20 years 16.5 Gy, and at 30 years 14.3 Gy. We have calculated 95% confidence limits for age at premature ovarian failure for estimated radiation doses to the ovary from 1 Gy to the ESD from birth to 50 years.

CONCLUSIONS

We report the first model to reliably predict the age of ovarian failure after treatment with a known dose of radiotherapy. Clinical application of this model will enable physicians to counsel women on their reproductive potential following successful treatment.