A 48-year-old woman with stage IIB clear-cell carcinoma of the ovary is being counseled about her treatment plan. Regarding the clinical features, prognostic factors, and management of clear-cell ovarian cancer, all of the following statements are true EXCEPT:

Explanation

## Clear-Cell Ovarian Cancer: Clinical Features and Prognosis ### Key Concept Clear-cell ovarian cancer is a distinct histological subtype with unique biological behavior, prognostic implications, and clinical associations. This question tests understanding of its chemosensitivity, associations, molecular features, and complications. ### Evaluation of Each Option **Option 1: Chemosensitivity and Prognosis — THE INCORRECT STATEMENT** **Key Point:** Clear-cell carcinoma is **chemoresistant** (not chemosensitive) to platinum-based therapy and has a **worse** prognosis than high-grade serous carcinoma at the same stage [cite:Park 26e Ch 16] - Response rate to platinum-based chemotherapy: 30–40% (vs. 60–80% in serous carcinoma) - 5-year overall survival: significantly lower than serous carcinoma at matched stages - This is a critical clinical distinction affecting treatment strategy **Option 2: Endometriosis Association (CORRECT)** - Clear-cell carcinoma is strongly associated with endometriosis, present in 30–50% of cases [cite:Park 26e Ch 16] - Association is particularly strong in early-stage disease - Endometriosis is considered a precursor lesion in some cases - This is a defining epidemiological feature of clear-cell cancer **Option 3: ARID1A Mutations (CORRECT)** - ARID1A mutations are present in 40–60% of clear-cell ovarian cancers [cite:Park 26e Ch 16] - ARID1A encodes BAF250a, a component of the SWI/SNF chromatin remodeling complex - Loss of BAF250a protein expression is immunohistochemically demonstrable - This molecular signature is a hallmark of clear-cell and endometrioid subtypes **Option 4: Thromboembolic Risk (CORRECT)** **Clinical Pearl:** Clear-cell ovarian cancer has a significantly higher propensity for thromboembolic complications (VTE, arterial thrombosis) compared to other epithelial subtypes [cite:Park 26e Ch 16] - Incidence of VTE: 5–10% in clear-cell vs. 1–2% in serous carcinoma - Mechanism: tissue factor expression, endothelial dysfunction, and cancer-associated thrombophilia - Prophylactic anticoagulation should be considered in high-risk patients ### Comparative Prognosis Table | Feature | Clear-Cell | High-Grade Serous | |---------|-----------|-------------------| | Platinum sensitivity | Low (30–40% response) | High (60–80% response) | | 5-year OS at stage IIB | ~50–60% | ~70–75% | | Endometriosis association | 30–50% | <5% | | ARID1A mutation rate | 40–60% | <5% | | VTE risk | 5–10% | 1–2% | ### High-Yield Summary **High-Yield:** Clear-cell ovarian cancer is **platinum-RESISTANT**, not platinum-sensitive. This is a high-yield exam fact and a critical clinical distinction that affects treatment decisions. **Mnemonic for Clear-Cell Features:** **CLEAR** - **C**hemoresistant (to platinum) - **L**ow prognosis (worse than serous) - **E**ndometriosis-associated - **A**RID1A mutations common - **R**isk of thromboembolism elevated