Phase II Trial of Cisplatin, Gemcitabine, and Intensity-Modulated Radiation Therapy for Locally Advanced Vulvar Squamous Cell Carcinoma: NRG Oncology/GOG Study 279

Abstract

Purpose: To assess efficacy and toxicity of cisplatin (C) and gemcitabine (G) with intensity-modulated radiation therapy (IMRT) in patients with locally advanced vulvar cancer not amenable to surgery.

Methods: Patients enrolled in a single-arm phase II study. Pretreatment inguinal-femoral nodal assessment was performed. Sixty-four Gy IMRT was prescribed to the vulva, with 50-64 Gy delivered to the groins/low pelvis. Radiation therapy (RT) plans were quality-reviewed pretreatment. C 40 mg/m² and G 50 mg/m² were administered once per week throughout IMRT. Complete pathologic response (CPR) was the primary end point. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method, and adverse events were assessed with Common Terminology Criteria for Adverse Events v 4.0.

Results: Fifty-seven patients enrolled, of which 52 were evaluable. The median age was 58 years (range, 25-58), and 94% were White. Forty (77%) had stage II or III disease, and all had squamous histology. A median of six chemotherapy cycles (range, 1-8) were received. Eighty-five percent of RT plans were quality-reviewed with 100% compliance to protocol. Seven patients came off trial because of toxicity or patient withdrawal. Of 52 patients available for pathologic assessment, 38 (73% [90% CI, 61 to 83]) achieved CPR. No pelvic exenterations were performed. With a median follow-up of 51 months, the 12-month PFS was 74% (90% CI, 62.2 to 82.7) and the 24-month OS was 70% (90% CI, 57 to 79). The most common grade 3 or 4 adverse events were hematologic toxicity and radiation dermatitis. There was one grade 5 event unlikely related to treatment.

Conclusion: Weekly C and G concurrent with IMRT sufficiently improved CPR in women with locally advanced vulvar squamous cell carcinoma not amenable to surgical resection.

Trial registration: ClinicalTrials.gov NCT01595061.

Figure 1:

Progression free survival (PFS) at 12 months and overall survival (OS) at 24 months. PFS was defined as the duration of time from study entry to the date of disease progression or death, whichever occurred first. PFS was censored on the date of last contact in patients who were alive and had no reappearance of disease. OS was defined as the duration of time from study entry to death or the date of last contact in patients who were alive. Kaplan-Meier method was used to estimate the distributions for PFS and OS.