A case of early-onset ovarian cancer following bariatric surgery: Highlighting the need for caution in genetically predisposed obese patients.

High-grade serous ovarian cancer (HGSOC) is the most lethal gynecologic malignancy, typically affecting postmenopausal women. BRCA1 mutation carriers are at increased risk of developing early-onset disease. While bariatric surgery reduces the incidence of several obesity-related cancers, its potential impact on hormonally driven malignancies in genetically predisposed individuals remains unclear. We report a rare case of early-onset HGSOC in a 21-year-old woman with morbid obesity and type 2 diabetes who underwent Roux-en-Y gastric bypass in 2010. Following significant weight loss, she regained regular menstruation and discontinued insulin therapy. After progressive weight regain, she underwent revisional bariatric surgery in 2020. Three years later, she presented with an ovarian cyst and elevated tumor markers. Imaging suggested malignancy, and biopsy confirmed HGSOC with a BRCA1 mutation. The patient underwent optimal cytoreductive surgery followed by chemotherapy and commenced olaparib maintenance therapy. As of September 2024, she remains disease-free. This case raises the concern that bariatric surgery, by restoring ovulatory function and altering metabolic and hormonal balance, may unmask a latent susceptibility to cancer in genetically predisposed patients. The temporal association between metabolic surgery and early-onset ovarian cancer warrants further investigation into postoperative hormonal shifts and cancer surveillance strategies. Bariatric surgery in women with hereditary cancer syndromes should be approached with caution. Preoperative genetic counseling, multidisciplinary assessment, and long-term oncologic surveillance are essential to ensure patient safety.