A 45-year-old woman presents with a pigmented lesion on her right thigh. She undergoes an incisional biopsy which reveals malignant melanoma with a thickness of 3 mm. Findings on examination of the groin are normal. Which of the following is the most appropriate next step in management?
Wide local excision with a 1-cm margin, followed by radiotherapy Wide local excision with a 1-cm margin and groin lymph node dissection Wide local excision with a 2-cm margin and sentinel lymph node biopsy Wide local excision with a 2-cm margin and groin lymph node dissection