The combination of gemcitabine, cisplatin, and intensity-modulated radiation therapy (IMRT) appears effective in patients with locally advanced, unresectable vulvar cancer, according to study results presented at the 2023 SGO Annual Meeting on Women’s Cancer.
The combination significantly improved outcomes when compared with chemoradiotherapy regimens given in prior trials, said study presenter Neil Horowitz, MD, of Brigham & Women’s Hospital and the Dana-Farber Cancer Institute in Boston.
The current phase 2 trial (GOG 279; ClinicalTrials.gov Identifier: NCT01595061) enrolled 57 patients with locally advanced, unresectable squamous cell carcinoma of the vulva, and 52 patients were treated.
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The median age of the cohort was 58 (range, 25-86) years, 94% of patients were White, 42% had stage II disease, and the median tumor size was 5 (range, 0-13) cm.
All patients received gemcitabine at 50 mg/m2 and cisplatin at 40 mg/m2 weekly throughout IMRT, which was given 5 days a week for 6 weeks. The IMRT dose to the vulva was 64 Gy, but doses to the groin varied according to lymph node status. Patients with resectable lymph nodes underwent lymph node dissection or sentinel lymph node biopsy prior to starting chemoradiotherapy.
Most patients (84%) completed therapy. Eight percent of patients withdrew due to toxicity, 6% refused to complete treatment, and 2% died.
The most common grade 3-4 adverse events were anemia (n=20), leukopenia (n=27), neutropenia (n=20), thrombocytopenia (n=20), and radiation dermatitis (n=18).
The rate of complete pathologic response (CPR) was 73.1%. Dr Horowitz noted, however, that the CPR rate could potentially have been as high as 90.4% because 17.3% of patients (n=9) were not evaluable for CPR due to a lack of biopsy.
The complete clinical response (CCR) rate was 71.2%, and the progression-free survival (PFS) rate at 12 months was 74%.
The efficacy outcomes in this trial were superior to outcomes in previous GOG trials, Dr Horowitz noted.
In GOG 205, patients received weekly cisplatin and 5670 cGy of anterior-posterior/posterior-anterior (AP-PA) radiotherapy. The CPR rate was 50%, the CCR rate was 64%, and the PFS rate at 12 months was 70%.
In GOG 101, patients received cisplatin plus fluorouracil and 4760 cGy of AP-PA radiotherapy. The CPR and CRR rates were 31% and 48%, respectively.
Disclosures: Dr Horowitz reported having no relevant disclosures.
Reference
Horowitz NS, Deng W, Peterson IA, et al. A phase II trial evaluating cisplatin and gemcitabine concurrent with intensity-modulated radiation therapy (IMRT) in the treatment of locally advanced squamous cell carcinoma of the vulva: NRG-GOG oncology trial #279. SGO 2023. March 25-28, 2023.
