DISEASE CHARACTERISTICS: Patients with malignant disease receiving chemotherapy regimen for at least 6 weeks but less than 6 months, and continuing concurrent chemotherapy for at least 3-4 weeks OR Patients with malignant disease receiving hormonal therapy for at least 3 months prior to study, and continuing during entire study Profile of Mood States (POMS) Fatigue Subscale score of 14 or higher POMS Depression Subscale score of 13 or less

PATIENT CHARACTERISTICS: Age: Over 17 Performance status: Karnofsky 70-100% Life expectancy: At least 3 months Hematopoietic: Hemoglobin at least 10 g/dL No decline in hemoglobin of 2 g/dL or more for one month prior to study Hematocrit at least 30% Hepatic: SGOT no greater than 3 times upper limit of normal Bilirubin less than 2.0 mg/dL Renal: Creatinine no greater than 2.0 mg/dL OR Creatinine clearance at least 60 mL/min Cardiovascular: No unstable cardiac disease Pulmonary: No debilitating pulmonary disease Other: No uncontrolled pain No uncontrolled serious infection No significant comorbidity that would preclude study participation Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: See Disease Characteristics Endocrine therapy: See Disease Characteristics Radiotherapy: Not specified Surgery: Not specified Other: At least 1 month since prior Hypericum perforatum (St. John's Wort) No other concurrent St.

John's Wort No concurrent monamine oxidase inhibitors (e.g., furazolidone, isocarboxazid, meclobremide, phenelzine, procarbazine, selegiline, and tranylcypromine) No concurrent sympathomimetic amines (e.g., amphetamine, phenylpropanolamine, and pseudoephedrine) or other stimulants such as methylphenidate No concurrent serotonin reuptake inhibitors (e.g., fluoxetine, paroxetine, sertraline, venlafaxine, nefazodone, mirtazepine, buspirone, and trazodone) or tricyclic antidepressants (e.g., amitriptyline, clomipramine, desipramine, doxepin, imipramine, nortriptyline, and protriptyline) No concurrent serotonergic agents (e.g., lithium, meperidine, and dextromethorphan) No concurrent active treatment for anemia (e.g., transfusions or epoetin alpha)