Pyridoxine in Preventing Hand-Foot Syndrome Caused by Capecitabine in Patients With Cancer

DISEASE CHARACTERISTICS: * Diagnosis of cancer * Must be receiving single-agent capecitabine either in the adjuvant/neoadjuvant or palliative setting at a dose of ≥ 1000 mg/m² twice daily on days 1-14 (given in 3-week courses) PATIENT CHARACTERISTICS: * Life expectancy \> 12 weeks * No preexisting neuropathy * No known allergy to pyridoxine hydrochloride and its incipients * No other dermatologic condition that, in the opinion of the physician, may affect the hands or feet or may complicate evaluation during study treatment PRIOR CONCURRENT THERAPY: * See Disease Characteristics * No prior capecitabine * Concurrent radiotherapy, steroids, and/or biological therapy (e.g., trastuzumab \[Herceptin®\] or bevacizumab) allowed provided they do not cause hand-foot syndrome (HFS) * No other concurrent drugs (e.g., docetaxel or doxorubicin hydrochloride liposome) that can cause HFS * No concurrent drugs (e.g., oxaliplatin or taxanes) that can cause neuropathy * No concurrent pyridoxine hydrochloride-containing preparations (e.g., multivitamins or vitamin B complex) * No concurrent over-the-counter products that contain urea or lactic acid * No concurrent drugs reported to have drug interactions with pyridoxine hydrochloride (e.g., cycloserine; hydralazine; immunosuppressants; isoniazid; levodopa; estrogen or estrogen-containing contraceptives; penicillamine; phenobarbitone; phenytoin; or pyrazinamide)