Case Study 6

For each question, choose the answer you think is correct. See the end of this page for the answers.

T.E. is a 19-year-old male diagnosed with primary intracerebral lymphoma. He is admitted to your hospital to receive chemotherapy treatment using the LYHDMRTEM protocol.

1. Which of the following statements best explains why T.E. is admitted to the hospital for his treatment?

T.E. doesn’t need to be admitted; LYHDMTXP chemotherapy can be administered in the outpatient setting
This is a potentially nephrotoxic regimen which requires administration in a hospital where rapid reporting of methotrexate levels is available
Due to the length of time for pre-hydration, treatment administration, and post-hydration, it is more convenient to treat T.E. as an inpatient
2 and 3 above

2. Which of the following statements best describes the purpose of leucovorin (folinic acid) in this treatment regimen?

Leucovorin exhibits synergy with methotrexate and helps to increase the cytotoxic properties of methotrexate
Leucovorin has antineoplastic properties that are ideally suited for the treatment of intracerebral lymphoma
Leucovorin reduces the toxicity of methotrexate by rescuing normal cells from the toxic effect of methotrexate
Leucovorin is added to help maintain a urine pH above 7

3. Which one of the following statements best describes the use of sodium bicarbonate in this treatment regimen?

Sodium bicarbonate is utilized to alkalinize the urine, keeping the pH greater than or equal to 7
Sodium bicarbonate is administered in both oral and intravenous forms
Sodium bicarbonate therapy is initiated prior to chemotherapy and continues until methotrexate levels are less than 0.1 micromole/L
All of the above

Answer 1

The correct answer is 4.

Rationale: The LYHDMTXP protocol states that “Methotrexate must be given in a hospital where rapid reporting of methotrexate levels is available”. The protocol also requires a leucovorin infusion to begin exactly 24 hours after the beginning of the methotrexate infusion and to continue until methotrexate levels are below 0.1 micromole/L. Pre- and post-methotrexate infusions of sodium bicarbonate and potassium are also required, which are more conveniently given if the patient is in a hospital. More information on the use of leucovorin with methotrexate may be found in Protectants [Clinical Pharmacy Guide - Module 5 - Supportive Care].

Answer 2

The correct answer is 3.

Rationale: Leucovorin reduces the toxicity of methotrexate by "rescuing" normal cells. In theory, it has been suggested that leucovorin has a preference for normal cells over certain tumour cells, due to a difference in their membrane transport mechanisms. This preference allows leucovorin to "rescue" normal cells from the toxic effects of methotrexate. See Protectants [Clinical Pharmacy Guide - Module 5 - Supportive Care] for more information.

Answer 3

The correct answer is 4.

Rationale: The LYHDMTXP protocol states that patients must have creatinine clearance greater than 60 mL/min and vigorous IV hydration and urine alkalinization to maintain urine pH above 7. Details of pre- and post-hydration and urine alkalinization are in the "Treatment" section of the protocol.