Topical Sildenafil as Pre-Treatment for Hand-Foot Skin Reaction

The purpose of this study is to evaluate the effect of topical sildenafil as a pre-treatment regimen for HFSR in patients naïve to anti-cancer therapy who will be initiated on treatment with sorafenib or sunitinib. The study endpoint will be the onset and calculated incidence of any grade of HFSR. Skin toxicity grading per National Cancer Institute - Common Terminology Criteria for Adverse Events (NCI-CTCAE) v4.03 will be performed by the investigator at each visit (every 2 weeks) until the end of the study (12 weeks total). This study aims to: 1. Determine whether HFSR can be prevented with topical sildenafil as pre-treatment. 2. Determine whether topical sildenafil can reduce the incidence of HFSR in patients treated with sorafenib or sunitinib. 3. Determine whether topical sildenafil can delay the onset of HFSR. 4. Determine whether topical sildenafil can reduce the severity of skin lesions if HFSR does occur. Patient Eligibility: The target population for this study is patients with clinically-diagnosed cancer who will be treated with sorafenib or sunitinib. A total of 20 subjects will be needed for this trial. There is no placebo group for this study. Subjects must meet all of the inclusion criteria and none of the exclusion criteria to be registered to the study. Data Collection: Patients will be instructed to apply the treatment cream to both hands and both feet twice a day for 12 weeks. After the initial visit to enroll and obtain consent, patient assessment will occur in clinic every 2 weeks. At each clinic visit, a skin toxicity grading per NCI-CTCAE v4.03 will be performed, any visual skin changes will be documented with photography, treatment cream will be refilled, and patient medication diaries will be reviewed. A follow up visit will occur within 30 days of the last study treatment. In addition, the investigators will collect information to ensure compliance with drug therapy (in the form of a subject medication diary).