Phase II Study of Concurrent and Sequential Carboplatin and Paclitaxel With Adjuvant Radiotherapy for High Risk Endometrial Cancer

Endometrial cancer is the most common gynecologic malignancy in the United States. Risk factors for development of endometrial cancer include increasing age, early menarche, late menopause, nulliparity, obesity, use of unopposed estrogen, and Lynch syndrome. The most common histology is endometrioid type adenocarcinoma, but less common, high-risk histologies include serous carcinoma, clear cell carcinoma, and carcinosarcoma. High risk stage I-II disease includes those with high risk histologies or any histology with multiple high risk features including deep myometrial invasion, high grade, and presence of extensive lymphovascular invasion. Locally advanced risk disease is routinely classified as Stage III-IVA. Despite treatment with adjuvant radiotherapy, chemotherapy, or combination radiotherapy and chemotherapy, relapse-free survival rates are 58-75% in modern series of GOG 258 and PORTEC-3. Therefore, there is significant need for improved therapies and optimization of combination therapy to improve these outcomes.

Standard initial management of endometrial cancer is total hysterectomy, bilateral salpingo-oophorectomy, and peritoneal washings with or without pelvic and paraaortic lymph node dissection. Endometrial cancer is surgically staged according the International Federation of Gynecologic Oncology (FIGO). Endometrioid type carcinomas most commonly present in an early stage, and several studies have established risk factors for recurrence including increasing depth of myometrial invasion, high grade, lymphovascular space invasion (LVSI), older age, greater tumor size, and increasing stage.

Historically, the rationale behind including adjuvant chemotherapy, either simultaneously with radiation therapy or sequentially, was the high rate of distant metastases despite lower pelvic failure rates with adjuvant radiation. The combination of chemotherapy and radiation therapy has additionally been shown to have greater survival compared either modality as monotherapy.

This study is designed to test the safety of adjuvant chemotherapy and radiotherapy with a novel regimen that addresses several of the hypotheses regarding the differing rate of distant metastases in GOG 258 while still using radiotherapy due to the locoregional control benefit from PORTEC-3.

To the knowledge of the investigators, no prospective study has reported on sequential and concurrent carboplatin and paclitaxel with EBRT for surgically managed endometrial cancer patients. With expeditious initiation of high dose systemic therapy and use of platinum/taxane combination chemotherapy concurrent with radiotherapy, we can address several potential hypotheses regarding the role that chemotherapy has to decrease the risk of distant metastases. Our primary objective is to assess the acute toxicities associated with sequential and concurrent carboplatin and paclitaxel with EBRT in the adjuvant management of endometrial cancer patients. If this regimen is safe, then its efficacy can be studied in a Phase III study.