Letrozole With or Without Paclitaxel and Carboplatin in Treating Patients With Stage II-IV Ovarian, Fallopian Tube, or Primary Peritoneal Cancer

PRIMARY OBJECTIVE: I. To examine if letrozole monotherapy/maintenance (L/L) is non-inferior to intravenous (IV) paclitaxel/carboplatin and maintenance letrozole (CT/L) with respect to progression-free survival (PFS) in women with stage II-IV primary low-grade serous carcinoma of the ovary or peritoneum after primary surgical cytoreduction. SECONDARY OBJECTIVES: I. To compare the nature, frequency and maximum degree of toxicity as assessed by Common Terminology Criteria for Adverse Events (CTCAE) version (v) 5.0 for each treatment arm. II. To compare the relative frequency of objective tumor response in those with measurable disease after cytoreductive surgery for each treatment arm. III. To compare overall survival for each treatment arm. IV. To compare the CT/L and L/L arms with respect to patients' adherence to letrozole therapy as measured by pill counts. OUTLINE: Patients are randomized to 1 of 2 arms. ARM I: Patients receive paclitaxel IV over 3 hours and carboplatin IV on day 1. Cycles repeat every 21 days for up to 6 cycles. Patients then receive letrozole orally (PO) once daily (QD) in the absence of disease progression or unacceptable toxicity. Patients undergo blood collection and tumor biopsy during screening as well as medical imaging throughout the study. ARM II: Patients receive letrozole PO QD. Cycles repeat every 21 days for up to 6 cycles. Patients then receive letrozole orally PO QD in the absence of disease progression or unacceptable toxicity as maintenance therapy. Patients undergo blood collection and tumor biopsy during screening as well as medical imaging throughout the study. After completion of study treatment/intervention, patients/participants are followed up every 3 months for 1 year, then every 6 months for 3 years, then annually thereafter.