A 2-month-old girl is found to have a small, hard mass on her scalp. The mass increases in size over the next 4 weeks. A biopsy is performed that confirms a diagnosis of embryonal rhabdomyosarcoma. You initiate chemotherapy with vincristine, dactinomycin, and cyclophosphamide. The child presents to clinic for day 1 of cycle 3 of chemotherapy, and the mass on her scalp is smaller. She is afebrile, absolute neutrophil count is 1,405 cells/mcL, platelet count is 154,000/mcL, and total bilirubin is 0.8 mg/dL. Her mother reports she looks very tired because her eyelids have been 'very droopy,' and she thinks she has a sore throat because her cry is hoarse. Her last bowel movement was 2 days ago. What is the most appropriate chemotherapy plan?
Correct Answer: C
Rationale: The correct answer is C because the child is showing signs of vincristine-induced neurotoxicity, which can manifest as droopy eyelids (ptosis) and hoarse cry. Holding vincristine and reevaluating weekly allows for monitoring of symptoms. If resolved, vincristine can be resumed with a dose reduction to prevent further neurotoxicity. Dactinomycin and cyclophosphamide are continued to maintain treatment efficacy. Continuing full-dose vincristine (choice A) can worsen neurotoxicity. With rhabdomyosarcoma responding to the current regimen, stopping all chemotherapy (choice B) is not appropriate. Discontinuing vincristine permanently (choice D) may compromise the treatment plan.