Lip cancers are considered oral cavity cancers. Lower lip cancers are more common than upper lip cancers. These cancers, even advanced cancers, uncommonly metastasize to the neck. Surgical excision, usually with a V excision is favored. One third of the length of the lip can be resected and primarily closed with good effect, and in select patients almost up to one half. Reconstruction of lip defects may require advanced rotational flaps like the Abbe, Estlander, or Karapandzic flaps. Larger defects can have significant effects on oral competence and quality of life.
Finally, the retromolar trigone (RMT) is where the body of the mandible transitions to the ascending ramus. Tumors that arise in this location are very close to bone and mandible. Resection may require marginal or segmental mandibulectomy with appropriate reconstruction.
The extent and impact of oral cavity cancer resection is defined by the tumor size, depth, and location. Because the oral cavity has many functions, small tumors or deep growing tumors in high function places, e.g. floor of mouth or retromolar trigone, can result in significant morbidity. This can be seen even with early stage cancers. Referral to an experienced head and neck oncologic surgeon is recommended to obtain the best possible functional and oncologic outcome for all oral cavity cancer.
With the exception of very thin early oral cavity cancers, management of the neck should be a consideration in all patients. In patients with a nodal disease (N+) a comprehensive neck dissection should be performed, to be followed by adjuvant radiation therapy. High risk features, such as lymph node extracapsular extension justify adjuvant chemoradiation.
Management of the neck in those patients without evidence of nodal disease (N0) varies. Early (T1,T2) oral cavity cancers can harbor microscopic nodal metastasis in 20-30% of cases . So all but the most superficial cancers warrant a staging neck dissection of at-risk lymph node basins for pathological analysis in the N0 neck. The at-risk regions are lymph nodes in the submandibular (level I), and upper cervical (level II/III) region . If microscopic disease is identified in the neck, this stages the patient as N+, and adjuvant radiation to the neck is recommended.
For cancers that are at, or cross, the midline, bilateral neck dissection should be considered.
Some authors have advocated observation, as opposed to neck dissection, for selected patients with the N0 neck. This is an area of controversy and is discussed in greater detail in the controversies section. (link)
Sentinel lymph node biopsy has also been considered for evaluating the N0 neck. This is also an area of controversy and is discussed in greater detail in the controversies section.