Clinical Review

Surgical management of head and neck malignancy

R.J. Sanderson and M-L. Montague
Edinburgh Cancer Centre, Western General Hospital, Edinburgh, EH4 2XU

Correspondence to: R.J. Sanderson, Edinburgh Cancer Centre, Western General Hospital, Edinburgh, EH4 2XU
Email:sandtol@ukgateway.net

Introduction Investigations Reconstruction

Classification of neck dissections Conclusion Acknowledgements References

Keywords: Surgery, head and neck, malignancy
Surg J R Coll Surg Edinb Irel., 2 February 2004, 7-14

More than 90% of head and neck tumours are squamous cell carcinomas. This review focuses on tumours arising from the mucosal surfaces of the upper aerodigestive tract. We discuss the aetiology, presentation and investigation of these tumours and give special attention to their management which may comprise surgical resection, chemoradiation or combined therapy. The surgical treatment of the clinically positive neck and the somewhat controversial topic of management of the N0 neck are also discussed

INTRODUCTION
Malignancy of the head and neck refers to tumours of the upper aerodigestive tract, the salivary glands, the thyroid and parathyroid glands, the sino-nasal tract and the skin of the head and neck. This article concentrates upon tumours arising from the mucosal surfaces of the upper aerodigestive tract. The majority of these tumours are squamous carcinomas (95%). Squamous carcinoma of the head and neck is one of the more common cancers on a worldwide basis with a high incidence in some countries, e.g. India. In the UK it is an uncommon cancer and only accounts for about 4% of all cancers. Its peak age of incidence is in the fifth and sixth decades and there is a male predominance of 3:1, although this ratio is now decreasing as the incidence in women increases. In Scotland, there is an increasing incidence in the disease and over the last ten years there has been an increase of 19.4% in males, but a very high increase of 28.7% in females.¹

AETIOLOGY
Tobacco, in association with alcohol and a poor diet are the main predisposing factors in the West, but in other parts of the world, e.g. India, other factors are of importance such as betel and areca nut chewing. The precise individual contribution of alcohol and tobacco in squamous carcinoma of the head and neck is not entirely clear as the two social habits of drinking and smoking often go together.² Whilst the products from tobacco smoke have been shown to be carcinogenic alcohol has not been shown to be so. It is thought that alcohol may act as a promoter in the development of carcinoma in association with inhalation of tobacco smoke. Nasopharyngeal carcinoma, which has a very high incidence in South-East China, is thought to be linked with Epstein Barr virus infection.³ Some histological and site specific carcinomas have individual causes such as the exposure to hardwood dust in people with adenocarcinoma of the ethmoid sinuses.⁴

PRESENTATION
Most head and neck cancers present with symptoms that are attributable to the primary site such as hoarseness, dysphagia or pain. Enlargement of a cervical lymph node is not uncommon particularly from so called ‘silent areas’ such as the base of the tongue, nasopharynx and supraglottis. Systemic metastases are uncommon at presentation (< 10%), but there is a significant incidence (10-15%) of synchronous and metachronous tumours of the upper aerodigestive tract.^5,6 Guidelines have been drawn up for other medical practitioners for the referral of patients with suspected head and neck malignancies (Table 1).⁷

There is evidence that removal of an involved cervical lymph node, without first identifying the source and nature of the primary is associated with an increase in morbidity and probably poorer long-term outcome.⁸ (See below)

INVESTIGATIONS
The diagnosis of a head and neck cancer is made on biopsy of the primary lesion and fine needle aspiration cytology (FNAC) of cervical lymphadenopathy (Figure 1). The tumour is staged according to the TNM classification system, which relies upon clinical and radiological parameters.⁹ This usually requires panendoscopy under general anaesthesia to assess the extent of the primary as well as to exclude synchronous primary upper aerodigestive tract tumours. Prior to panendoscopy it is preferable to have imaging of the head and neck performed as biopsies of the tumour sites can produce distortion of the radiological image and result in upstaging of the tumour.

Figure 1: Microscopic examination of a cervical lymph node aspirate identifying typical malignant squamous cells (Giemsa stain, magni.cation x600) 

IMAGING
Radiological imaging is of great importance in the staging of head and neck tumours, both in assessing the extent of the primary tumour and in documenting cervical and distant metastases. Within the head and neck there are often different requirements for the imaging of each subsite.

PRIMARY LESION
Computerised tomography (CT) scanning remains the mainstay in imaging head and neck tumours due to its general availability. It is particularly useful in evaluating the relationship of tumours to bone (Figure 2 and 3). It has the advantages over magnetic resonance imaging (MRI) in that acquisition times are faster, it is less claustrophobic and cheaper. Also, MRI has some advantages over CT in that soft-tissue contrast is better, there is no dental amalgam artefact, multiplanar reconstruction is possible and there is no exposure to ionising radiation (Figure 4 and 5). In some situations, both CT and MRI are necessary to evaluate the tumour extent.

Figure 2: Axial CT scan of a T4 laryngeal tumour with extensive cartilage destruction 

Figure 3: Axial CT scan of a T3 tumour of the left piriform fossa with ipsilateral cervical lymph node metastases

Figure 4: Magnetic resonance imaging (MRI) scan (axial cut) showing tumour arising from the right tongue base 

Figure 5: MRI scan (coronal cut) demonstrating tumour of the left side of the nasopharynx

NECK NODE METASTASES
Neck node metastases are identified on CT and MRI scanning on size criteria and/or the presence of central necrosis (Figure 6).¹⁰ There is some debate as to which method is better at detecting involved neck nodes but, in practice, CT is used more often due to its general availability. The use of ultrasound must be mentioned in the detection of cervical lymph node metastases. When ultrasound is combined with FNAC the pick-up rates of cervical metastases are said to be superior to CT or MRI.¹¹

DISTANT METASTASES
CT is the most common form of imaging in looking for distant metastases and it is now common practice to scan the lungs along with the head and neck. The value of this is still debatable with some authors advocating and others rejecting its use.^12,13 In the UK, there is an increasing trend to perform a screening chest scan. Liver metastases are rare in head and neck cancer, but some units also routinely perform an ultrasound examination of the liver to exclude metastases before embarking on treatment. Most units, however, do not routinely screen the liver except in the case of carcinomas that have a higher propensity to distant metastases such as nasopharyngeal carcinoma.

RECURRENT DISEASE
Recurrent disease is often difficult to detect both clinically and radiologically, whatever modality is used. Positron emission tomography (PET) may have a role in detecting recurrent disease but  its limited accessibility makes its use scarce.¹⁴

TREATMENT OF HEAD AND NECK CANCER
The treatment of head and neck cancer requires the input of a multidisciplinary team that includes the different members of the medical and paramedical professions. The British Association of Otolaryngologists - Head and Neck Surgeons have guidelines for the minimum constitution of the team.¹⁵ (Table 2). As head and neck cancer encompasses tumours at a large number of subsites often invading more than one subsite each has its own particular issues regarding management. Patients who suffer from this disease are often in poor general health and may have significant co-morbidities and psychosocial issues.

The management of head and neck cancer has to be considered with respect to the primary tumour and cervical lymph node metastases.

PRIMARY SITE
Radiotherapy and surgery both offer equally good results in early stage squamous carcinoma. There is a trend for surgical treatment in early diseases when conservation surgery can be performed. The choice of treatment regimen is often dependent upon which institution a patient is referred to, rather than any good clinical evidence that one treatment plan is better than another. Indeed, in head and neck cancer, there is often a lack of well-controlled clinical trials and most reported series are retrospective and descriptive. Given the fact that there is often no good evidence that one treatment produces better survival than another the final treatment plan is often decided by other factors.

One of the most important factors in deciding treatment is post-treatment morbidity. Because of the morbidity associated with large surgical resections, especially with respect to speech, swallowing and cosmesis, there is a growing trend towards employing organ preservation strategies, either with the use of chemoradiation or, increasingly, the use of the laser to resect upper aerodigestive tract tumours.

There are, however, several circumstances where surgery is of proven benefit over radiotherapy.

These include:

• The treatment of large palpable neck nodes from squamous carcinoma of the head and neck (excluding nasopharyngeal carcinoma) 

• The treatment of radiation failures where radiotherapy can’t be given again or new tumours developing in a  previous radiation field

• The treatment of radiation resistant tumours e.g. acinic cell tumours

• The treatment of tumours where there is cartilage and/or bone invasion.

Figure 6: Axial computerised tomography (CT) scan showing central necrosis within a left cervical lymph node metastasis

The use of the CO₂ laser in treating head and neck carcinomas is increasing in popularity. This is especially true of early stage laryngeal disease as treatment can be performed on a day-case basis and the results, with regard to recurrence, are equivalent to radiotherapy thus, obviating the need for a four to six week course of radiotherapy treatment.¹⁶ It is still debatable which treatment modality (laser or radiotherapy) gives the best voice results.¹⁷ The laser is also being used for lesions of the oral cavity, oropharynx and hypopharynx. The laser is used to remove the tumour endoscopically with only a small margin of normal tissue (confirmed on frozen section), thus, trying to preserve as much normal tissue as possible. The resulting defect is left to heal by primary intention. One of the claimed benefits is that the area, when it has healed, is sensate. This is very important in the restoration of swallowing and speech, and, thereby, post-operative normal function in the patient is probably improved. Whilst it is generally accepted that the post-operative function of the patient is generally better than after conventional surgery, there is debate as to whether function is better than with conventional radiotherapy treatment. No long-term studies comparing function following radiotherapy with that after laser treatment exist. In some centres, most primary tumours of the larynx, hypopharynx, oropharynx and oral cavity are treated with the laser, including T3 and T4 lesions. Steiner et al. (2001) have reported excellent results with the use of the laser in terms of survival, and also claim good functional outcomes, even for advanced lesions, although a proportion of the patients still require post-operative radiotherapy.¹⁸ More studies are needed, on both survival and functional outcomes, from other centres.

Figure 7a: The radical neck dissection

Figure 7b: Modi.ed radical neck dissection (Type 2) with preservation of the internal jugular vein and spinal accessory nerve

Figure 7c: Selective neck dissection (Lymph node levels II-IV) 

Figure 7d: Extended neck dissection (common carotid artery resected)

RECONSTRUCTION
Despite the advances in cancer treatment over the years there is limited evidence that survival in head and neck cancer has improved. This is partly explained by other factors such as the development of metachronous tumours of the aerodigesive tract, and death from cardiorespiratory problems, which these patients often have. There is evidence that loco-regional control of the disease has improved but, unfortunately, if locoregional disease is controlled then with time there is an increasing incidence of distant metastases being seen.

One aspect that has certainly improved over the years is the ability to close large defects of the head and neck that follow excision. This first started with the introduction of pedicled myocutaneous flaps, which enabled excision and reconstruction in one operation and reduced time spent in hospital. More recently, free flaps are being used, these having the advantage that they can almost be tailor made to fit the defect with usually only minor donor site morbidity. There are several free flaps that as well as supplying skin coverage also supply bone which is of great advantage when bony defects need to be reconstructed. One of the problems with flaps is lack of normal sensation and, although anatomically most head and neck defects can be repaired, function is not always good.

Large and previously inaccessible tumours that were deemed unresectable previously, can now, with new surgical approaches, sometimes be resected; for example, nasopharyngeal and skull base tumours and tumours extending into the mediastinum. These approaches often need the input of other surgical disciplines such as neurosurgery or cardiothoracic surgery.

CHEMO-RADIATION
If resection of the primary tumour results in great morbidity (e.g. glossectomy), then most units would treat the primary cancer with radiotherapy in an attempt to reduce this morbidity. The Meta-analysis of Chemotherapy on Head and Neck Cancer (MACH-NC) Collaborative Group looked at chemotherapy, in addition to loco-regional treatments.¹⁹ The analysis showed a significant benefit to concurrent chemotherapy with an absolute benefit of 8% at five years. Thus, chemo-radiation is increasing in popularity as a method of treating advanced squamous cell carcinoma of the head and neck. When there is significant palpable cervical lymphadenopathy it is usual to treat the neck surgically (neck dissection) and the primary and/or neck with chemo-radiotherapy, in those patients who are judged suitable for chemo-radiation. Whether the neck should be treated before the primary or as a planned neck dissection following chemoradiotherapy is not clear.

THE NECK
The single most important prognostic factor in squamous carcinoma of the head and neck is the presence of involved lymph nodes in the head and neck. The presence of a single involved lymph node reduces survival by 50%.²⁰ Hence, consideration must be given to treatment of the neck. It is generally accepted that if the chance of lymph node metastases in the neck is greater than 20% then the neck needs treatment.²¹ This applies to the majority of head and neck tumours regardless of stage, the exceptions being lip, early glottic, lower alveolar ridge and sino-nasal cancer.

Consideration has to be given to treating both sides of the neck in midline, tongue base, nasopharyngeal and supraglottic lesions where there is a high incidence of bilateral metastatic disease.

THE N0 NECK
The treatment of the N0 neck remains a somewhat controversial area in head and neck surgery. If the primary tumour has a greater than 20% expected incidence of neck node metastases then the neck should be treated. Although there is no prospective randomised trial comparing a watch and wait policy with active treatment of the N0 neck there is some evidence to support this view, especially in oral cancer.²²

Once it has been decided to treat the N0 neck the next decision is how? If the primary tumour is being treated with radiotherapy then the neck can also be treated with radiotherapy, as it has been shown that radiotherapy will eliminate 95% of nodal metastases.²³ If the primary tumour is treated with surgery, then the neck is usually treated in the same manner. The question that needs to be asked is what kind of neck dissection is adequate treatment for the N0 neck?

CLASSIFICATION OF NECK DISSECTIONS
Surgical dissections of the neck can be classified into four types based on the classification system of the American Academy of Otolaryngology and Head and Neck Surgery.²⁴

• Radical neck dissection: Levels I to V dissected, including resection of the internal jugular vein,sternomastoid muscle and accessory nerve (Figure 7a)

• Modified neck dissection: Levels I to V dissected but preserving one or more of the accessory nerve, internal jugular vein or sternomastoid muscle (types I, II and III, respectively) (Figure 7b)

• Selective neck dissection: Denotes preservation of one or more lymph node groups (levels I to V) and preservation of the accessory nerve, internal jugular vein and the sternomastoid muscle (Figure 7c)

• Extended neck dissection:As in radical neck dissection but with removal of one or more additional lymphatic and/or non-lymphatic structure(s) (Figure 7d).

It is accepted that the classical radical or extended neck dissection has no role in the treatment of the N0 neck as these cause most morbidity due to the sacrifice of the accessory nerve, giving rise to a sore and stiff shoulder. The choice is between a modified and a selective neck dissection.

As tumours from each site within the head and neck metastasise in a reasonably predictive fashion to certain levels of the neck, it is possible to tailor a selective neck dissection accordingly.²⁵ Thus, for oral cavity and oropharynx levels I to IV should be cleared. For laryngeal and hyopharyngeal tumours, levels II to IV should be cleared. A recent study looking at laryngeal cancer has shown a selective neck dissection, clearing levels II to IV, is as effective as a type III modified neck dissection.^29,30 Biopsy to a cervical node containing metastatic carcinoma prior to definitive treatment does increase morbidity.³¹ It remains, therefore, good practice not to biopsy a neck node without first performing fine needle aspiration and carefully looking for a possible primary lesion, especially in people over 40 years who are smokers and drinkers.²⁶ The advantage of a selective over a modified neck dissection is that the accessory nerve, although preserved in both, has better function after a selective neck dissection. If more than one involved node is found in a selective neck dissection or there is extra-capsular spread then post-operative radiotherapy to the neck is normally given.

SENTINEL NODE BIOPSY
There is increasing evidence that there may be a role for sentinel node biopsy in squamous carcinoma of the head and neck, especially in oral and oropharyngeal tumours.²⁷ After identifying the sentinel node by injecting blue dye and/or radiocolloid into the primary tumour this node can be sent for frozen section to see if it contains malignant cells. A neck dissection must be performed if the node is involved. If the sentinel node is clear then a neck dissection may be avoided. This technique has the potential to reduce the rate of neck dissection in squamous carcinoma of the head and neck. Preliminary studies are encouraging in the use of this technique.

THE CLINICALLY INVOLVED NECK
When the neck is clinically involved, a type I modified neck dissection is usually performed as this causes less morbidity than the standard radical neck dissection due to preservation of the accessory nerve. The exception to this is if there is direct tumour involvement of the accessory nerve, internal jugular vein or sternomastoid muscle. A modified neck dissection has been shown to be as oncologically sound as a standard neck dissection when combined with post-operative radiotherapy.²⁸  In the instance of a truly occult primary tumour and, in the presence of nodal disease in the neck (confirmed for squamous cell carcinoma on FNAC) a radical or modified radical neck dissection should be performed. Further treatment with radiotherapy or chemo-radiation is governed by the stage of nodal disease and the presence of poor or good pathological prognostic features.

BIOPSY OF A NODE CONTAINING SQUAMOUS CELL CARCINOMA
A review by McGuirt and McCabe (1978) of 64 patients who had a cervical lymph node excised or biopsied prior to definitive treatment, showed that rates of neck recurrence, distant metastases and wound breakdown were significantly higher than in those patients who had not undergone biopsy prior to definitive treatment. 8 Other authors have been unable to show this where the neck was irradiated.

CONCLUSION
Although the survival from head and neck cancer has not increased greatly over the last 30 years, the morbidity from its treatment has. Reducing morbidity associated with the treatment of head and neck cancer is very important, as even if these patients are cured from their tumour, they have a high incidence of death from cardiovascular and respiratory factors secondary to their smoking habits. Surgical treatment times are a lot shorter when reconstruction of a defect is required, with the introduction of myocutaneous and free flaps. Tumours that were previously inaccessible have become accessible especially with new techniques in skull base surgery. There is presently a trend for organ preservation surgery to reduce post treatment morbidity still further and the laser shows much promise in this, as well as the use of chemo-radiotherapy in treating the primary tumour. Surgery still plays the major role in treating the neck with tumour involved nodes, but modifications in the type of neck dissection have reduced morbidity from this procedure.

ACKNOWLEDGEMENTS
The authors wish to thank Dr. William Wallace (Consultant Pathologist, Royal Infirmary of Edinburgh), Dr. Donald Collie (Consultant Radiologist, Department of Clinical Neuroscience X-ray, Western General Hospital, Edinburgh) and Miss. Heather Scott (Department of Medical Illustration, Queen Margaret Hospital, Dunfermline) for providing cytological and radiological images and medical illustrations respectively.

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Copyright: 22 September 2003