Ovarian Cancer for USMLE Step 1
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Ovarian Cancer for the USMLE Step 1 Exam
Ovarian Cancer
- Epidemiology:
- Ovarian cancer has a high mortality rate among gynecologic cancers due to its tendency for late-stage presentation.
- Risk Factors:
- Increased age, especially postmenopausal women (50–70 years).
- Family history of ovarian or breast cancer.
- BRCA1/BRCA2 mutations and Lynch syndrome, both of which significantly elevate risk.
- Increased lifetime ovulation (nulliparity, early menarche, late menopause).
- Protective Factors:
- Oral contraceptives, pregnancy, and breastfeeding, which reduce ovulatory cycles.
Types of Ovarian Cancer
- Epithelial Tumors:
- Account for approximately 90% of ovarian cancers and are classified by cell type:
- Serous Carcinomas: Most common and often high-grade.
- Mucinous Carcinomas: Less common; may grow large.
- Endometrioid and Clear Cell Carcinomas: Frequently associated with endometriosis.
- Low-Grade vs. High-Grade Serous Tumors: High-grade serous carcinomas are more aggressive, presenting at later stages.
- Germ Cell Tumors:
- Originate from germ cells, primarily affect younger women, and have a good prognosis when treated.
- Types include dysgerminomas, yolk sac tumors, and immature teratomas.
- Sex Cord-Stromal Tumors:
- Arise from ovarian stromal tissue, producing hormones that can cause symptoms like abnormal uterine bleeding.
- Granulosa Cell Tumors: Produce estrogen, which can lead to symptoms like endometrial hyperplasia.
- Sertoli-Leydig Cell Tumors: Produce androgens, which may cause virilization.
Clinical Presentation
- Symptoms:
- Often asymptomatic in early stages; common symptoms in advanced stages include:
- Abdominal bloating or distension.
- Pelvic or abdominal pain.
- Early satiety.
- Urinary urgency or frequency.
- Advanced Disease: May present with ascites, bowel obstruction, or pleural effusion.
- Physical Exam:
- Findings may include a palpable abdominal or pelvic mass, ascites, or pleural effusion (if metastasis has occurred).
Diagnosis
- Imaging:
- Pelvic Ultrasound: First-line imaging for adnexal masses, with malignant features including solid areas, thick septations, papillary projections, and ascites.
- CT Scan of the Abdomen and Pelvis: Used for staging and assessing metastatic disease.
- Laboratory Tests:
- CA-125: A tumor marker often elevated in epithelial ovarian cancer, though it lacks specificity.
- Other Tumor Markers:
- AFP, hCG, and LDH: Used to evaluate germ cell tumors.
- Inhibin: Elevated in granulosa cell tumors.
- Histopathology:
- Required for definitive diagnosis, usually obtained through surgical exploration or biopsy.
Staging
- FIGO Staging:
- Stage I: Confined to the ovaries.
- Stage II: Involves the pelvis.
- Stage III: Spread to abdominal organs or lymph nodes.
- Stage IV: Distant metastasis (e.g., pleural effusion, liver parenchyma).
Treatment
- Surgical Treatment:
- Debulking Surgery: Main treatment in advanced stages, involving removal of the ovaries, fallopian tubes, uterus, omentum, and affected tissues.
- Fertility-Sparing Surgery: Considered in young patients with early-stage disease.
- Chemotherapy:
- Platinum-Based Chemotherapy: Standard treatment for epithelial tumors, typically carboplatin and paclitaxel.
- Germ Cell Tumors: Respond well to BEP regimen (bleomycin, etoposide, and cisplatin).
- Targeted Therapy:
- PARP Inhibitors: Effective in BRCA-mutated ovarian cancers, inhibiting DNA repair in cancer cells.
- Anti-Angiogenic Therapy: Bevacizumab (anti-VEGF) can be used in advanced cases to inhibit tumor blood supply.
Key Points
- Ovarian Cancer is often asymptomatic until advanced stages; epithelial tumors are the most common type.
- Risk Factors include age, family history, BRCA mutations, and high lifetime ovulatory cycles, while protective factors include oral contraceptive use and pregnancy.
- Diagnosis relies on ultrasound and CA-125 marker, with definitive diagnosis by histopathology.
- Staging follows the FIGO system, with prognosis worsening at later stages.
- Treatment involves debulking surgery and chemotherapy, while targeted therapies like PARP inhibitors and anti-angiogenics (bevacizumab) are used in specific cases.