What is the treatment approach for a patient diagnosed with endometrioid carcinoma of the ovary?

Treatment of Endometrioid Carcinoma of the Ovary

Endometrioid carcinoma of the ovary should be treated with comprehensive surgical staging followed by risk-stratified adjuvant therapy, with carboplatin plus paclitaxel as the standard chemotherapy regimen for advanced disease, following the same treatment paradigm as epithelial ovarian cancer. 1

Initial Surgical Management

Primary treatment consists of total hysterectomy with bilateral salpingo-oophorectomy and comprehensive surgical staging, including pelvic and para-aortic lymphadenectomy. 1 The minimal surgical procedure must include:

• Acquisition of peritoneal fluid or washings 1
• Thorough exploration of the abdominal cavity and pelvic/para-aortic nodal areas 1
• Total hysterectomy with bilateral salpingo-oophorectomy 1
• In high-risk cases, omentectomy and retroperitoneal lymph node dissection are often recommended, though their survival benefit remains unclear 1

For advanced disease (stages III-IV), maximal surgical cytoreduction should be performed in patients with good performance status. 1

Critical Diagnostic Consideration

Before finalizing treatment, perform gastrointestinal tract evaluation and measure CEA levels to exclude metastatic gastrointestinal primary masquerading as ovarian endometrioid carcinoma, as metastases to the ovaries are more common than primary ovarian endometrioid tumors. 1 PAX8 immunostaining may be useful for this distinction 1. Endometrioid carcinomas are typically positive for CK7, PAX8, CA 125, and estrogen receptors 1.

Stage-Specific Adjuvant Treatment

Stage IA/IB (Low-Risk)

For stage IA or IB, grade 1 or 2 endometrioid histology: observation only with no adjuvant therapy. 1

Stage IC to II Disease

For stage IC to II endometrioid carcinoma, the standard adjuvant treatment is intravenous carboplatin (AUC 5-6) plus paclitaxel (175 mg/m²) every 3 weeks. 1, 2, 3 Alternative options include:

• Observation (category 2B recommendation) 1
• Hormone therapy with anastrozole, letrozole, leuprolide, or tamoxifen (category 2B for all hormone therapy options) 1

The chemotherapy regimen should follow dosing recommendations for epithelial ovarian cancer 1.

Stage III-IV (Advanced Disease)

For stages III-IV endometrioid carcinoma, the standard treatment is cisplatin plus doxorubicin combination chemotherapy, which significantly improves both progression-free survival and overall survival compared with whole abdominal radiation therapy with pelvic boost. 1

Due to toxicity considerations, carboplatin (AUC 5-6) plus paclitaxel (175 mg/m²) every 3 weeks is an acceptable alternative regimen. 1 This combination should be administered for 6 cycles 4.

Specific chemotherapy details:

• Carboplatin should not be repeated until neutrophil count ≥2,000 and platelet count ≥100,000 2
• Paclitaxel courses should not be repeated until neutrophil count ≥1,500 cells/mm³ and platelet count ≥100,000 cells/mm³ 3
• Dose reductions of 20% are required for severe neutropenia (neutrophils <500 cells/mm³ for ≥1 week) 3

Patients with Positive Peritoneal Cytology Only

Patients with stage III disease based solely on positive peritoneal cytology should be treated according to their stage I or II classification based on other clinicopathological data. 1

Role of Radiation Therapy

Pelvic radiotherapy increases locoregional control but does NOT improve overall survival in endometrioid ovarian carcinoma. 1 Radiation may be considered for:

• Intermediate-risk patients with ≥2 of 3 major risk factors (age ≥60 years, deeply invasive tumors, or grade 3 histology) who have locoregional relapse rates >15% 1
• High-risk stage I disease to increase locoregional control, though distant metastases remain problematic 1

Special Considerations for Hormone-Responsive Disease

Progestational agents (medroxyprogesterone acetate 200 mg daily) are active in steroid-receptor positive tumors, particularly grade 1 and 2 lesions. 1 However, adjuvant progestational agents in low-stage endometrial cancer do not increase survival and are NOT recommended. 1

Synchronous Endometrial Cancer

Approximately 11-12% of patients with endometrioid ovarian carcinoma have synchronous endometrial cancer. 5, 6 These patients should be staged according to their ovarian cancer and treated based on that stage 6. Survival analysis shows a trend toward longer survival in patients with synchronous tumors 6.

Prognostic Factors

The most important independent prognostic factors are:

• FIGO surgical stage (most significant in multivariate analysis) 6
• Histological grade 6
• Residual disease after surgery 6
• Lymph node status 6
• Platinum-based chemotherapy 6

Achievement of complete clinical response is the strongest predictor of survival, regardless of chemotherapy type used. 5

Common Pitfalls to Avoid

• Do not treat endometrioid ovarian carcinoma differently from other epithelial ovarian cancers - the treatment paradigm is identical, with surgery followed by platinum-based chemotherapy for advanced disease 1
• Do not omit gastrointestinal evaluation - failing to exclude metastatic GI primary can lead to inappropriate treatment, as true primary ovarian endometrioid tumors are uncommon 1
• Do not use progestational agents as adjuvant therapy in early-stage disease - they do not improve survival 1
• Do not rely on radiation alone for advanced disease - chemotherapy is superior for stages III-IV 1
• Do not confuse with sex cord-stromal tumors - immunohistochemical markers are essential for accurate diagnosis when cord-like structures are prominent 7