Background: Fertility-sparing treatment may be offered as an alternative to standard surgical management of early-stage, well-differentiated endometrial cancer in young women. Immunostaining for progesterone receptor (PR) status is not currently part of the standard workup before treatment recommendations are made.
Case: We describe a 29-year-old woman who used oral contraceptive pills on a long-term basis in whom early-stage, well-differentiated endometrial cancer was diagnosed. Progestin therapy failed and the tumor was subsequently found to be PR negative.
Conclusion: Combination oral contraceptive pills may stimulate clonal expansion of endometrial cells that lack PR, leading to endometrial adenocarcinoma unresponsive to progestin therapy. Consideration should be given to PR immunostaining for confirmation of the receptor status and evaluation of appropriate management options when counseling patients about fertility-sparing therapy.