Trial of IIb Preserving Neck Dissection
Condition: Oral Cancer
MeSH terms: Mouth Neoplasms
Study type: Interventional

Summary: 
      The treatment of clinically N0 neck in malignancies of oral cavity is controversial. The
      options include the policy of "wait and watch"(close observation and follow-up), elective
      irradiation of the neck, elective surgery of the neck (neck dissection).

      In elective neck dissections, the procedures commonly performed are modified radical neck
      dissection-III (functional neck dissection) and selective (supraomohyoid) neck dissection
      depending on the site of the primary lesion within the oral cavity. There are no trials of
      IIb preserving neck dissection in cancers of the oral cavity.
    

Detailed description: 
      Surgery of the cervical lymphatic system has evolved a lot since the introduction of
      classical radical neck dissection by Crile in 1906, which was later established by Martin
      (1945). It includes the removal of cervical lymphatic levels I-V along with removal of
      non-lymphatic structures namely submandibular gland, tail of parotid, omohyoid muscle,
      cervical plexus of nerves, spinal accessory nerve, internal jugular vein and
      sternocleidomastoid muscle. The main morbidity of the radical neck dissection was the
      trapezius muscle dysfunction with shoulder drop, resulting in pain and shoulder dysfunction.
      The other morbidities of radical neck dissection were cosmetic deformity of neck, painful
      neuromas, increased facial swelling, numbness of neck and ear.

      In the last three decades, many modifications of the classical radical neck dissection
      (modified radical neck dissections), had been described and are increasingly applied. The
      main modifications have been the preservation of one or more of the non-lymphatic structures
      that were removed in classical radical neck dissection mainly the spinal accessory nerve,
      internal jugular vein, sternocleidomastoid muscle (Bocca and Pignataro, 1967). The reasons
      for developing these modifications were functional and cosmetic, while preserving the
      oncological safety of the procedure.

      Much later in 1980s, the concept of selective neck dissection, for which Lindberg (1972) and
      Skolnik (1976) laid down important basis, was introduced. In selective neck dissections only
      those groups of lymph nodes are removed, which, depending upon the location of the primary
      tumour, are most likely to contain metastasis (Shah, 1990).

      The first selective neck dissection introduced was the supraomohyoid neck dissection, which
      includes the removal of lymph node levels I-III, while preserving the non-lymphatic
      structures as functional neck dissection. Medina and Byers in a prospective study have
      demonstrated the utility of this supraomohyoid neck dissection in patients with clinically
      negative neck nodes (N0) with malignancies of oral cavity.

      The posterolateral neck dissection removes lymph node levels II-V as well as retroauricular
      and suboccipital nodes, which is used primarily for treatment of tumours of scalp and post
      auricular skin.

      The lateral neck dissection, which includes removal of lymph node levels II-IV, is done for
      tumours of larynx or hypopharynx with N0 neck.

      The anterior compartment neck dissection includes removal of only lymph node level VI which
      is done in thyroid malignancies when there is no evidence of lateral lymphadenopathy, and is
      combined with lateral neck dissection(anterolateral) if there are lymphnodes involved.

      Recently the concept of superselective neck dissections has been introduced. It is less
      radical than selective neck dissections, removing lesser number of at-risk lymph nodal
      groups.

      H Coskun (2004) found IIb preserving superselective neck dissection as oncologically safe
      procedure in N0 laryngeal cancer, with more functional preservation of trapezius muscle and
      hence negligible shoulder disability. In this study, it was found that even in selective neck
      dissection, some degree of spinal accessory nerve dysfunction and shoulder disability occurs
      as a result of retraction of the nerve during the clearance of the lymph nodes posterior and
      superior to the nerve (IIb). If these lymph nodes were not removed and left in place, there
      would be no stretching of spinal accessory nerve during the neck dissection and shoulder
      disability could be avoided
    

Intervention name(s): Selective neck dissection; Conventional Neck dissection
Intervention type(s): Procedure; Procedure
Intervention description(s): Level IIb preserving neck dissection; Conventional neck dissection (MRND type III or Supraomohyoid)
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Oral; cancer; surgery; neck dissection; spinal accessory nerve