Head and neck cancer is on the increase, with oral tongue squamous cell carcinoma (OTSCC) comprising 25–40% of all oral carcinoma. Despite the progress made in cancer management and the introduction of multidisciplinary treatment modalities, the overall survival has not improved in the past 30 years. Thus, a refinement of the treatment strategy is needed.
The human tongue is unique and yet disadvantaged for its unfavourable orthogonally orientated muscle fibres, which accelerate the progression of tumour spread to a deeper tissue plane. In addition, enriched neurovascular bundles and the lymphatic network make tongue cancer prone to regional metastasis.
The tumour edge is far from being rectilinear. Discohesive cells of the tumour foci can migrate along muscle fibres following the path of least resistance far beyond the wide surgical resection margin. This indicates that conventional wide surgical resection of 1–2-cm circumference beyond the macroscopic margins is insufficient to fulfil the radicality concept. Furthermore, the borders of the OTSCC are difficult to appreciate preoperatively, especially when the musculature is twitching and contracting unpredictably.
With regard to regional metastasis, the lingual nodes are the first echelon lymph nodes for OTSCC. Yet, many surgeons are not aware of the lingual lymphatic system, which comprises the median lingual node, lateral lingual node, and lingual node at the root of the lingual artery. It is well unknown that occult lingual node metastases are difficult to identify preoperatively due to their small size and close proximity to the primary lesion (overshadowed by the prominent primary lesion and sublingual gland). Meanwhile, the lingual nodes are the intermediate lymph nodes. The tumour spreading through the lymphatic channel might not necessarily reside within the lingual node but enter the cervical lymph node directly ( Fig. 1 ). Nevertheless, the continuous lymphatic vessels running along the intervening tissues in the floor of mouth before entering the submandibular region are overtly present. Also, the lingual node at the root of the lingual artery (beneath the hyoglossus muscle) is never included in either pull-through or conventional en bloc resection. These remnants of the lymphatic system left in situ are prone to relapse. If relapse occurs, a total laryngectomy may be required or it may just be unsalvageable.
Therefore, a change in resection technique towards compartment resection is needed. Compartment resection is a longitudinal resection of the involved muscle fibres from their origin to insertion points, respecting the normal boundaries. An advantage of this resection is the radical removal of the entire potential path of spread. Furthermore, detachment of the hyoglossus and mylohyoid muscle ( Fig. 2 ) from the hyoid bone is effective in bringing the lingual lymphatic system into the surgical field, allowing it to be removed together with the cervical lymphatic chain. This is very important, as the lateral lingual node cannot be removed trans-cervically in conventional neck dissection. Therefore an improved anatomical understanding and technical refinement of strategies for resection of primary cancer could improve loco-regional control.