Ovarian Cancer

Detailed Overview

Ovarian cancer is the leading cause of death from gynecologic malignancies. It is dubbed the 'silent killer' because it remains asymptomatic in early stages; over 70% of patients are diagnosed at an advanced stage (III or IV) when the cancer has spread throughout the peritoneal cavity. While the disease is highly responsive to platinum-based chemotherapy initially, recurrence and chemoresistance are common. Germline and somatic BRCA1/2 mutations play a major role in its pathogenesis and open avenues for targeted therapy with PARP inhibitors.

Epidemiology & Demographics

Causes over 13,000 deaths annually in the US. Median age at diagnosis is 63 years. Lifetime risk is about 1.3% for the general female population, but increases dramatically (up to 40-60%) in women with BRCA mutations.

Etiological Mechanism

The exact etiology is debated, but the 'incessant ovulation' hypothesis suggests that repeated trauma and repair of the ovarian epithelium during ovulation predisposes to malignant transformation. More recently, overwhelming evidence shows that High-Grade Serous Carcinoma originates from Serous Tubal Intraepithelial Carcinoma (STIC) lesions in the fimbriae of the fallopian tubes.

Primary Causes

Germline mutations (BRCA1, BRCA2, Lynch Syndrome)

Incessant ovulation (nulliparity, early menarche, late menopause)

• BRCA1 and BRCA2 Mutations: Defects in homologous recombination DNA repair drastically increase risk.
• Age and Repro History: Older age, nulliparity (never having children), and fertility treatments increase risk.
• Endometriosis: Specifically increases the risk of Clear Cell and Endometrioid ovarian carcinomas.

In High-Grade Serous Carcinoma, p53 mutations occur early in the fallopian tube epithelium (forming a p53 signature). This progresses to STIC, which eventually exfoliates malignant cells. These cells implant onto the ovary and the peritoneum. The cancer spreads primarily via transcoelomic dissemination (shedding into the peritoneal cavity) following the normal flow of peritoneal fluid, leading to diffuse carcinomatosis, omental caking, and malignant ascites. Implantation on the diaphragm blocks lymphatic drainage, exacerbating ascites.

Characteristic Clinical Presentation

• Abdominal bloating: Increased abdominal girth due to ascites or a large pelvic mass.
• Pelvic or abdominal pain: Vague, persistent pain.
• Early satiety: Feeling full quickly after eating a small amount, due to stomach compression by ascites/tumor.
• Urinary symptoms: Urgency or frequency due to mass effect on the bladder.

Physical Examination Signs

• Palpable, solid, fixed, irregular adnexal mass on bimanual pelvic exam.
• Shifting dullness and fluid wave (signs of ascites).
• Sister Mary Joseph nodule (umbilical metastasis) or palpable supraclavicular node.

• Bowel Obstruction: Due to tumor compressing or infiltrating the intestines; a common cause of death.
• Malignant Ascites: Massive fluid accumulation causing severe respiratory compromise and discomfort.
• Venous Thromboembolism (VTE): High rate of DVT and PE due to the prothrombotic state of malignancy.

Diagnostic Criteria & Guidelines

Diagnosis and staging are surgical. Preoperatively, suspicious ultrasound findings (solid components, thick septations, ascites) combined with elevated CA-125 suggest the diagnosis. Definitive diagnosis requires surgical pathology from tumor resection or biopsy.

Differential Diagnosis

• Benign Ovarian Cysts (Follicular, Corpus Luteum)
• Endometriomas
• Uterine Fibroids
• Gastrointestinal malignancy (e.g., Colon Cancer, Krukenberg tumor)
• Diverticulitis

Laboratory Tests & Biomarkers

• CA-125: Elevated (>35 U/mL) in 80% of advanced epithelial ovarian cancers. Used for monitoring response to therapy, not as a general screening tool.
• Genetic Testing: All women diagnosed with epithelial ovarian cancer must undergo germline and somatic BRCA1/2 testing and Homologous Recombination Deficiency (HRD) testing.

Imaging Modalities & Findings

• Transvaginal Ultrasound (TVUS):
• CT Abdomen/Pelvis:

• Stage I
  Tumor confined to ovaries or fallopian tubes.
• Stage II
  Tumor involves one or both ovaries with pelvic extension (e.g., uterus, rectum).
• Stage III
  Tumor spread to the peritoneum outside the pelvis and/or retroperitoneal lymph node metastasis.
• Stage IV
  Distant metastasis (e.g., liver parenchyma, pleural effusion with positive cytology).

Second-Line & Adjunctive Therapy

Maintenance Therapy: For patients with BRCA mutations or HRD-positive tumors who respond to platinum chemotherapy, PARP inhibitors (e.g., Olaparib 300 mg PO BID or Niraparib) are used to significantly prolong progression-free survival. Bevacizumab (anti-VEGF) is also used for maintenance in advanced stages.

Surgical & Procedural Management

Aggressive cytoreductive surgery. The survival of the patient is directly correlated with the volume of residual disease left behind. Bowel resections and splenectomy may be necessary to remove all visible tumor.

Recommended Lifestyle Changes

• Maintain nutrition and hydration during chemotherapy.
• Discuss fertility preservation options before surgery in young patients with early-stage disease.

Patient Counseling & Advice

Inform the patient that while ovarian cancer responds very well to initial chemotherapy, the risk of recurrence is high (over 70% for advanced disease). Discuss the importance of genetic testing not only for their own targeted therapy (PARP inhibitors) but to alert family members who might need prophylactic surgery.

Follow-Up & Monitoring Schedule

History, physical exam, and CA-125 levels every 3 months for 2 years, then every 6 months for 3 years. CT scans are performed if there is clinical suspicion of recurrence or rising CA-125.

Preventive Strategies

For high-risk BRCA mutation carriers, risk-reducing salpingo-oophorectomy (RRSO) between ages 35-40 (after childbearing) reduces risk by 80-90%. Oral Contraceptive Pills (OCPs) for >5 years reduce risk by 50% in the general population.

5-year survival for Stage I is >90%. For Stage III/IV, 5-year survival drops to 30-40%. Despite high initial response rates to chemotherapy, most advanced cases recur and eventually become platinum-resistant.