Objective Distinguishing between advanced stage endometrial and ovarian cancer at diagnosis can be challenging, especially when patients do not present with abnormal uterine bleeding. Given emerging systemic therapies specific for ovarian versus endometrial cancers, it has become increasingly critical to establish the correct diagnosis at presentation to ensure appropriate treatment. This study evaluates the frequency with which advanced endometrial cancer is mistakenly presumed to be ovarian cancer.

Methods A retrospective analysis was performed of patients with a final diagnosis of advanced endometrial cancer treated consecutively at a single academic institution between 2013 and 2022. Variables abstracted included abnormal uterine bleeding, endometrial sampling, and timing of endometrial cancer diagnosis. We quantified incorrect diagnoses made after 2018, when frontline targeted treatments differentiating advanced endometrial from advanced ovarian cancer became available.

Results We identified 270 patients with an ultimate diagnosis of stage III or IV endometrial cancer. The most common presenting symptom was abnormal uterine bleeding (219/270, 81%), followed by abdominal or pelvic pain (48/270, 18%) and bloating (27/270, 10%). Forty-eight patients (18%) received neoadjuvant chemotherapy, of whom 11 (23%) had an incorrect diagnosis of ovarian cancer. Since 2018, six patients have received neoadjuvant chemotherapy for presumed ovarian cancer, three of whom received a systemic regimen specific for ovarian cancer when they, in fact, had endometrial cancer.

Conclusion In patients with presumed advanced ovarian cancer dispositioned to neoadjuvant chemotherapy, endometrial sampling can identify some cases that are actually primary endometrial cancers. Correct diagnosis guides the use of appropriate antineoplastic therapies, optimizing response and survival outcomes while minimizing toxicity and cost of unindicated therapies.