There is ‘little evidence’ that the use of conventional fertility hormones used for ovarian stimulation in the treatment of infertility increases the long-term risk of breast and gynecological cancers, according to the results of a substantial 30-year follow-up study. The study was a retrospective investigation involving 12,193 women treated for infertility between 1965 and 1988 at five US sites. A total of 9,892 women were successfully followed for cancer outcomes.