NCT04008563.

Study name	Bariatric surgery for fertility‐sparing treatment of atypical hyperplasia and grade 1 cancer of the endometrium (B‐FiERCE)
Methods	Parallel, unblinded, 2‐arm, randomised controlled trial
Participants	Women aged 18–41 years, BMI ≥ 35 kg/m2, with a diagnosis of grade endometrioid endometrial cancer or complex atypical hyperplasia, with clinical stage 1 disease, with an ECOG PS < 2, with a desire for fertility preservation and with no contraindications to progestin intrauterine device.
Interventions	Experimental: bariatric surgery and progestin intrauterine device. Participants will receive a progestin intrauterine device and be referred for bariatric service to undergo bariatric surgery within 3 months of their study consent. No intervention: progestin intrauterine device alone.
Outcomes	Primary outcomes: recruitment rate (to determine proportion of eligible women who agree to participate in study (recruitment rate). Primary outcome will be met, and a full‐scale randomised controlled trial to assess efficacy will be conducted if ≥ 40% recruitment rate is achieved. Patients' reasons for participation or non‐participation will be recorded.) Secondary outcomes: completion of bariatric surgery; loss to follow‐up rate; completion of Patient Reported Outcome Questionnaires and complete response rate: time to complete response, overall recurrence rate and time to recurrence.
Starting date	July 2019
Contact information	Sarah E Ferguson, University Health Network, Toronto, Canada
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