Ovarian Epithelial Cancer: Causes, Staging, and Treatment Options — Overview, Diagnosis & Treatment Options | MyMedicPlus

Ovarian epithelial cancer is the most common form of ovarian malignancy, accounting for approximately 90% of all ovarian cancers. It arises from the surface epithelium of the ovary or from the fallopian tube epithelium, with high-grade serous carcinoma (HGSC) being the predominant histological subtype. Other subtypes include clear cell, endometrioid, mucinous, and low-grade serous carcinoma. Globally, ovarian epithelial cancer is the fifth leading cause of cancer death among women, with roughly 207,000 deaths per year. It predominantly affects postmenopausal women, with peak incidence between ages 55 and 64. Because early-stage disease is often asymptomatic and reliable screening tools are lacking, approximately 75% of cases are diagnosed at advanced stage (FIGO III–IV), contributing to its high mortality rate. Five-year survival for stage I disease exceeds 90%, dropping to under 30% for stage IV.

The pathogenesis of ovarian epithelial cancer involves accumulation of genetic mutations affecting tumor suppressor genes and oncogenes. The most significant hereditary risk factor is germline mutation in BRCA1 or BRCA2, conferring a lifetime risk of 40–60% and 15–25%, respectively. Lynch syndrome (mismatch repair gene mutations) increases risk primarily for endometrioid and clear cell subtypes. Sporadic cases are associated with incessant ovulation theory — each ovulatory cycle causes micro-trauma and repair, increasing mutation risk. Risk factors include nulliparity, early menarche, late menopause, endometriosis (especially for clear cell and endometrioid types), hormone replacement therapy, and obesity. Protective factors include oral contraceptive use (reducing risk by ~50% with 5+ years of use), breastfeeding, bilateral salpingo-oophorectomy, and tubal ligation.

Early ovarian epithelial cancer is typically asymptomatic, making diagnosis challenging. When symptoms do appear, they are often nonspecific and mimic benign gastrointestinal or urinary conditions. Common symptoms include persistent abdominal bloating or distension, pelvic or abdominal pain, difficulty eating or early satiety, and urinary urgency or frequency occurring daily for more than two to three weeks. Other manifestations include unexplained weight loss, fatigue, back pain, dyspareunia, and irregular vaginal bleeding in premenopausal women. Red flags warranting urgent evaluation include rapidly increasing abdominal girth due to ascites, new-onset bowel obstruction symptoms, or a fixed pelvic mass on examination. The constellation of bloating, early satiety, pelvic pain, and urinary symptoms appearing together is now recognized as the Ovarian Cancer Symptom Index.

Diagnosis begins with transvaginal ultrasound (TVUS), which assesses ovarian morphology, septations, solid components, and vascularity using the IOTA classification system. Serum CA-125 is the primary biomarker; elevated levels above 35 U/mL support malignancy, though CA-125 is less reliable in premenopausal women. HE4 (human epididymis protein 4) in combination with CA-125 improves specificity through the ROMA score algorithm. CT of chest, abdomen, and pelvis with contrast is essential for staging and surgical planning. MRI may better characterize indeterminate adnexal masses. PET-CT is used for equivocal lymph node assessment. Definitive diagnosis requires histopathology from surgical resection or, in unresectable disease, image-guided biopsy. FIGO 2021 staging guides treatment: Stage I (confined to ovary), Stage II (pelvic extension), Stage III (peritoneal spread or retroperitoneal lymph nodes), Stage IV (distant metastasis). BRCA1/2 germline testing and somatic tumor HRD (homologous recombination deficiency) testing are standard.

Treatment follows NCCN and ESMO guidelines. For early-stage disease (FIGO I–II), the standard is comprehensive surgical staging — total abdominal hysterectomy, bilateral salpingo-oophorectomy, omentectomy, pelvic and para-aortic lymph node dissection, and peritoneal biopsies — followed by carboplatin plus paclitaxel chemotherapy for 3–6 cycles in all except stage IA/IB grade 1 tumors. For advanced disease (FIGO III–IV), primary debulking surgery (PDS) aimed at achieving no gross residual disease is the gold standard, followed by 6 cycles of carboplatin/paclitaxel ± bevacizumab. In patients unfit for upfront surgery, neoadjuvant chemotherapy (NACT) for 3 cycles followed by interval debulking surgery is an acceptable alternative. Maintenance therapy with PARP inhibitors — olaparib, niraparib, or rucaparib — significantly prolongs progression-free survival in BRCA-mutated and HRD-positive patients. Bevacizumab maintenance is used in HRD-negative patients. Recurrent disease is managed based on platinum-free interval: platinum-sensitive recurrence (>6 months) receives platinum re-challenge plus PARP inhibitor; platinum-resistant disease uses liposomal doxorubicin, gemcitabine, or topotecan.

The prognosis of ovarian epithelial cancer is primarily determined by FIGO stage at diagnosis and residual disease after primary surgery. Five-year overall survival by stage: Stage I exceeds 90%; Stage II reaches 70–80%; Stage III drops to 25–45%; Stage IV falls below 30%. The achievement of no gross residual disease (R0) at primary debulking surgery is the single most important prognostic factor for advanced-stage disease — patients with R0 have median OS of 50–60 months versus 30–35 months for those with any gross residual disease. BRCA1/2-mutated tumors are more chemosensitive, resulting in better initial response rates, and derive the greatest benefit from PARP inhibitor maintenance therapy. PARP inhibitor maintenance (olaparib, niraparib) after first-line platinum-based chemotherapy extends progression-free survival by 18–36 months in BRCA-mutated or HRD-positive patients. Despite initial responses, approximately 70–80% of advanced-stage patients relapse within 18–24 months. Platinum-free interval (PFI) is the key determinant of subsequent treatment response: platinum-sensitive recurrence (PFI >6 months) responds well to re-challenge; platinum-resistant disease (PFI <6 months) has median OS of 6–12 months with available salvage therapies. Histological subtype influences prognosis: clear cell and mucinous carcinomas are less platinum-sensitive and carry worse outcomes for advanced stages. Long-term monitoring includes CA-125, clinical assessment, and imaging guided by symptoms or rising markers at 3-monthly intervals for 2 years, then 6-monthly thereafter.

There is no reliable population-level screening strategy for ovarian epithelial cancer; CA-125 and TVUS screening have not shown mortality benefit in unselected populations (UKCTOCS trial). Prevention focuses on risk modification. Combined oral contraceptive pills used for five or more years reduce lifetime risk by approximately 50%. Risk-reducing salpingo-oophorectomy (RRSO) is strongly recommended for BRCA1 carriers (typically at age 35–40) and BRCA2 carriers (at 40–45) after childbearing is complete, and also for Lynch syndrome patients. Risk-reducing salpingectomy alone may be considered in lower-risk women. Genetic counseling and cascade testing of first-degree relatives of BRCA mutation carriers is essential. Lifestyle factors including maintaining healthy weight, regular physical activity, and breastfeeding provide modest protective benefit.

Women should seek urgent evaluation if they experience persistent bloating, pelvic or abdominal pain, difficulty eating, or urinary symptoms occurring more than 12 times per month — particularly if these are new, frequent, and severe. Any postmenopausal vaginal bleeding warrants prompt gynecological assessment. A palpable pelvic or abdominal mass, rapidly increasing abdominal girth, or unexplained significant weight loss requires urgent referral to a gynecologist or gynecologic oncologist. Women with a personal or family history of breast or ovarian cancer, or known BRCA1/2 mutation, should be seen by a genetic counselor and a gynecologic oncologist for risk assessment and surveillance planning. Symptoms of intestinal obstruction — severe constipation, inability to pass gas, vomiting — require emergency evaluation, as these may indicate advanced peritoneal disease.