Inclusion Criteria:  Recruited patients will be limited to those with a biopsy-proven in situ or superficially invasive (does not invade past the papillary dermis) squamous cell carcinoma of the skin of the low risk or "L" areas. The tumor must measure 1.0-2.0cm in longest diameter dimension. Tumors must lack induration and/or nodularity. The tumor must also demonstrate positive margins on review of the original biopsy pathology (biopsy must be partial; there must be residual tumor that requires further treatment). Patient has capacity to provide consent  Exclusion Criteria:  Immunocompromise or immunosuppression. Contraindication to surgical excision. Contraindication to use of topical medication(s) (e.g., history of allergic contact dermatitis to topical 5-fluorouracil) Currently pregant, concerned could be pregnant, actively trying to conceive, or missed last menstrual period that is not explainable by birth control method (5-Fluorouracil is pregnancy category X) Tumor is recurrent