Initially start with PEG insertion: For this purpose, insertion with the gastroscope under laryngoscopic control. Easy pre-scopy into the stomach. Here, with excellent diaphanoscopy, problem-free puncture of the stomach and insertion of the PEG tube using the usual thread pull-through method. The oesophagus is inconspicuous on reflection. Repositioning of the patient for transoral tumor resection. Insertion of the open mouth blocker. Re-inspection: The exophytic tumor process can be seen in the area of the underside of the tongue on the left side. The anterior floor of the mouth is not reached. Small leukoplakic extensions in the surrounding area, but with a relatively well-defined tumor process. Incision around the tumor with a safety margin of 1 cm. Depth infiltration approx. 0.5 cm. Involvement of the tongue muscles. The excretory duct can remain intact. The resectate is thread-marked for frozen section diagnostics and is diagnosed as completely tumor-free in the area of the margins. Careful hemostasis. Repositioning of the patient for neck dissection. Injection of xylocaine with added adrenaline. Submandibular skin incision and start with the left side. Cut through skin and subcutaneous tissue. Separation and dissection of the platysma. Exposure of the sternocleidomastoid muscle, omohyoid muscle and digastric muscle. Exposure and preservation of the external jugular vein. Exposure of the digastric muscle does not reveal a truly pronounced submandibular gland. Therefore, elevation of the ramus marginalis mandibulae and clearing of level Ib. The anterior margin shows a clearly suspicious lesion without surrounding infiltration. Removal of level Ib. Exposure of the anterior venter of the digastric muscle. Complete evacuation of level Ia via the left side. Complete the neck dissection, exposing and preserving the facial vein, the superior thyroid artery, the cervical artery and the hypoglossal nerve. Exposure of the accessory nerve. Clearing of the accessorius triangle. Here there are conspicuous changes in both Level IIa and Level IIb, especially in Level IIa clinically metastatic lesions. Clearing of level V with careful protection of the cervical plexus branches. Clearing up to the transition to level Vb. No evidence of lymphatic leakage caudally. Careful exposure of the internal jugular vein, common carotid artery and vagus nerve. Final wound inspection, wound irrigation. Turn to the opposite side. After exposing the muscular borders, the submandibular gland is regularly exposed. Evacuation of level Ib with careful protection of the ramus marginalis mandibulae. Then complete to level Ia. Clearing of levels IIa to IV with careful preservation of the facial vein, the superior thyroid artery and the cervical sinus. Exposure and preservation of the accessorius nerve. Limitation of the extension towards level V. No further measures and no suspicious nodes. Careful wound irrigation. If the wound is dry, final inspection of the wound cavities. Insertion of a 10-gauge Redon drain and careful two-layer wound closure. Final enoral inspection and, if the wound is dry, completion of the procedure without any indication of complications. Conclusion: Intraoperative R0-resected cT2 cN2b oral cavity carcinoma in the area of the underside of the tongue on the left. After receiving the definitive histology, adjuvant therapy was also determined with regard to the secondary diagnosis of TBC disease.