Lip carcinoma most commonly occurs in:

The majority of lip malignancies present on the lower lip (88 to 98%), followed by the upper lip (2 to 7%) and oral commissure (1%). The histology of lip cancers is predominantly squamous cell carcinoma; however, other tumors, such as keratoacanthoma, verrucous carcinoma, basal cell carcinoma, malignant melanoma, minor salivary gland malignancies, and tumors of mesenchymal origin (e.g., malignant fibrous histiocytoma, leiomyosarcoma, and rhabdomyosarcoma), may also present in this location. Basal cell carcinoma presents more frequently on the upper lip than lower. Ref: Schwaz's principle of surgery 9th edition, chapter 18.