A 52-year-old patient complains about a nonhealing ulcer on his lower lip. The patient is smoker. He hasn't ever consulted a doctor about it. In the region of red border of the lower lip a roundish ulcer is present. It is up to 2,0 cm in diameter. The ulcer edges are thickened and a little bit raised in form of a whitish swelling. In the left submandibular region palpation revealed enlarged, painless, dense lymph nodes with limited mobility. What is the most likely diagnosis?