Chemotherapy induced nausea is a common side effect for children undergoing chemotherapy. Furthermore, chemotherapy-induced vomiting is a major factor limiting quality of life during treatment reported by paediatric cancer survivors. Complete prevention of both nausea and vomiting is the goal of anti-vomiting and nausea medications. It is important to understand whether or not certain chemotherapeutic treatments are more or less likely to cause these symptoms. Acute leukemia is the most common cancer diagnosed in children. Intrathecal methotrexate is an important part of chemotherapy for the prevention and treatment of central nervous system leukemia over the 2.5 to 3.5 years of the treatment program for leukemia. The likelihood that intrathecal methotrexate administered as monotherapy will cause nausea and vomiting has not yet been described in children. Knowledge of the likelihood that intrathecal methotrexate will cause nausea and vomiting will therefore be important to optimize treatment for these side-effects of chemotherapy. The primary aim of this prospective study is to evaluate the potential of intrathecal methotrexate to cause nausea and vomiting in paediatric cancer patients.

Inclusion Criteria:

• 4 years old to 18 years of age (age range in which the PeNAT has been validated) [18]
• English speaking (PeNAT has been validated only in English)
• Cognitive ability of the child believed to be at least at a 4 year old level according to parent or health care professional
• Patients are past their first cycle of maintenance therapy to avoid interactions with the intensive chemotherapy phase.

Exclusion Criteria:

• Receiving chemotherapy other than dictated by protocol for maintenance therapy within 24 hours prior to or 24 hours following receipt of intrathecal methotrexate

Receiving intrathecal methotrexate in the context of maintenance therapy for acute lymphoblastic leukemia and as dosed by age per protocol. Patients will also receive their protocol driven maintenance chemotherapy which includes oral 6 mercaptopurine and may include IV vincristine and an oral steroid pulse (prednisone or dexamethasone). Oral methotrexate is typically held the weeks that patients receive intrathecal methotrexate during maintenance therapy.