A Pilot Phase II Trial of Radiation Therapy "Sandwiched" Between Paclitaxel and Carboplatin in Patients With Uterine Papillary Serous Carcinoma

Uterine papillary serous carcinoma (UPSC) is an uncommon, but aggressive variant of endometrial carcinoma that has a high recurrence rate and poor response to therapy. It has a propensity to metastasize throughout the abdomen, similar to serous carcinoma of the ovary. In fact, many patients with disease apparently confined to the uterus have microscopic intra-abdominal spread at the time of diagnosis. Recurrences are common both in the pelvis as well as in the upper abdomen.

After staging and debulking of gross disease, adjuvant radiation therapy is recommended to treat patients with endometrial carcinoma at high risk for recurrent disease. High-risk features include histologic cell type, grade, depth of myometrial invasion, cervical extension, lymph-vascular invasion, adnexal involvement, intraperitoneal spread, positive peritoneal cytology, and positive lymph nodes. Pelvic radiation can limit local recurrences to less than 6.5%. However, approximately 25-30% of patients with high-risk features who receive radiation recur with distant metastases. Even patients treated with whole abdominal irradiation are at risk for extra-abdominal recurrences with progression-free intervals of 7 to 8 months.

Adjuvant chemotherapeutic regimens have been studied in high-risk endometrial cancers, but none have demonstrated a survival advantage. Doxorubicin, in combination with platinum, has a reported 42% response rate, but a high toxicity profile. Paclitaxel has an overall response rate of 36% in patients with advanced and recurrent endometrial cancer. Platinum-based chemotherapies have a 28-42% response rate.

Retrospective studies in patients with UPSC have demonstrated response rates of up to 35% in patients with multiagent chemotherapy. In one study, a median progression-free interval of 30 months was observed in patients treated with paclitaxel and platinum in the adjuvant and recurrent settings. Based on these findings and the similarities and clinical success of paclitaxel/platinum therapy in patients with ovarian serous carcinoma, this combination warrants further investigation in a prospective manner in patients with UPSC.

Combination chemo/radiotherapy trials in advanced/recurrent endometrial cancer are ongoing. The optimal radiation modality, chemotherapeutic agents, and sequence of these regimens for the treatment of UPSC are yet to be established. A retrospective review of 16 patients treated at our institution with the sequential use of radiation "sandwiched" between paclitaxel/platinum chemotherapy found only one patient to have recurred at 16 months with a median follow-up of 15 months (range 6-33 months). The regimen was well tolerated. Eight of the sixteen patients (50%) developed grade 3 neutropenia following cycle 4 of chemotherapy, two of which required a 1 week treatment delay. There were no cases of grade 3 or 4 thrombocytopenia noted. There was no febrile neutropenia and no hospital admissions for toxicity. There were no observed grade 3 or 4 non-hematologic toxicities. With the median follow up of 15 months, we have not observed late toxicities.