Topical chemotherapy ointments, often used for skin cancer, will typically cause a deep sore or ulcer on the skin as the main side effect. Learn how doctors may use topical chemotherapy for a short period and then stop for a period of time to let the skin heal with information from adoctor in this free video on chemotherapy and cancer treatments. Expert: Dr. David Cathcart Bio: Dr. David Cathcart has been an occupational medicine physician at Heartland Regional Medical Center in St. Joseph …