OBJECTIVES:~To evaluate the tolerability and usefulness of the dietary supplement, L-carnitine L-tartrate, in the prevention of chemotherapy-induced peripheral neuropathy in women with metastatic breast cancer.~OUTLINE: Patients are randomized to 1 of 2 treatment arms.~Arm I: Patients receive oral L-carnitine L-tartrate twice daily beginning on day 2 of the first course of chemotherapy and continuing until after completion of 4 courses of chemotherapy.~Arm II: Patients receive oral placebo twice daily beginning on day 2 of the first course of chemotherapy and continuing until after completion of 4 courses of chemotherapy.~Patients complete questionnaires periodically to assess neuropathy, pain, fatigue, sleep, and activities of daily living.~After completion of study treatment, patients are followed at 4 weeks and then every 3 months thereafter.
RATIONALE: L-carnitine L-tartrate may prevent peripheral neuropathy caused by chemotherapy.~PURPOSE: This randomized clinical trial is studying how well L-carnitine L-tartrate works in preventing peripheral neuropathy caused by chemotherapy in women with metastatic breast cancer.