Radiation Therapy With or Without Cisplatin in Treating Patients With Stage I, Stage II, or Stage III Cancer of the Vulva

DISEASE CHARACTERISTICS: * Histologically confirmed stage I, II, III, or IVA squamous cell carcinoma of the vulva amenable to curative treatment with surgery, radiotherapy, or both * At least 1 positive inguinal and/or femoral lymph node * No inoperable (fixed or ulcerating) groin nodes * Must not require resection of urethra or anal sphincter to achieve negative margins * Must have undergone vulvar biopsy and bilateral inguinal/femoral lymph node dissection within 8 weeks of randomization * No metastatic disease PATIENT CHARACTERISTICS: Age: * Any age Performance status: * GOG 0-2 Life expectancy: * Not specified Hematopoietic: * WBC at least 3,000/mm\^3 * Platelet count at least 100,000/mm\^3 * Granulocyte count at least 1,500/mm\^3 Hepatic: * Bilirubin no greater than 1.5 times normal * SGOT no greater than 3 times normal * Alkaline phosphatase no greater than 3 times normal Renal: * Creatinine no greater than 2.0 mg/dL Other: * Not pregnant or nursing * Fertile patients must use effective contraception * No other prior invasive malignancy within the past 5 years except nonmelanoma skin cancer PRIOR CONCURRENT THERAPY: Biologic therapy: * Not specified Chemotherapy: * No prior chemotherapy Endocrine therapy: * Not specified Radiotherapy: * See Disease Characteristics * No prior radiotherapy Surgery: * See Disease Characteristics * No more than 8 weeks since prior surgery Other: * No prior therapy for another malignancy that would preclude study