Around 1 in 5 women with low-grade endometrioid ovarian cancer are found to also have co-existent endometrial cancer at diagnosis. Co-existent endometrial and ovarian cancer (CEOC) patients typically have very favorable outcomes; however, many are treated as advanced stage. Treatment varies greatly and patients are often given chemotherapy or pelvic radiation, despite unclear benefit and substantial toxicity from treatment-related side effects such as neuropathy, fatigue and cognitive issues. Overtreatment also results in financial challenges for patients and families from loss of income, travel expenses related to many appointments and delayed return to work.

Using a new system of molecular and pathological criteria, doctors can identify far more patients with excellent outcomes (49% of CEOCs vs 20% using older criteria). These individuals may be candidates for treatment de-escalation, meaning they could be spared unnecessary treatment-related toxicity.

The aim of this pragmatic clinical trial is to determine the safety of de-escalated/optimized adjuvant treatment of patients with CEOC directed by tumor molecular status and strictly defined pathology criteria.

Outcomes & Impact. Defining a group of patients with CEOC who can be considered for treatment de-escalation through both molecular and pathological refinement could more than double the number of patients who could forego adjuvant therapy without increased risk of recurrence or death. Many more patients could be spared the significant short and long-term side effects of chemotherapy and radiation, with anticipated improved quality of life and reduced financial burden on patients.