Management of the primary tumour
Choice of
treatment
The principal treatments available for primary
tumours remain surgery and radiotherapy. The basic decision to be made is
between radical radiotherapy and elective surgery. If the former is chosen,
surgery is reserved for ‘salvage’, i.e. for biopsy proven recurrent or
residual disease. If surgery is chosen, radiotherapy may be used in an adjuvant
manner, either preoperatively or postoperatively, but the operation remains
fundamentally the definitive curative procedure. Preferences for one or other
policy vary considerably between treatment centres.
Many
factors must be considered in deciding the optimum management for each
individual patient. These include the sire, stage and histology of the tumour,
and the medical condition and lifestyle of the patient. Ideally, every patient
should be seen at a joint consultation clinic by a surgeon and radiotherapist
who assess objectively and agree the optimum strategy of management for the
particular individual. The following factors should influence the decision on
treatment policy.
Site of origin
The choice of treatment depends on the part of
the mouth in which the tumour arises. The management of primary tumours at the
various anatomical sites is discussed later. In general, surgery is preferred
for those tumours arising on or involving the alveolar processes; for other
sires surgery and radiotherapy are alternatives.
Stage of
disease
A small lesion which can be excised readily
without producing any deformity or disability is, in general, best managed
surgically. Surgery is also usually more appropriate for a very large mass or
where there is invasion of bone, provided the tumour is operable, because of the
low cure rates by radiotherapy in these circumstances. The management of lesions
of intermediate stage, i.e. larger Ti, most T2 and early exophytic T3 tumours,
is more controversial as policies of elective surgery or radical radiotherapy
produce generally similar survival rates; hence, discussion centres on the
likely functional results and morbidity of either approach.
When
there is involvement of cervical lymph nodes the primary and nodes are normally
both treated surgically. However, there is no clear evidence that a primary
tumour is less likely to be cured by radiotherapy in the presence of lymph node
metastases than in their absence.
Previous
irradiation
It is not advisable to retreat a tumour
arising in previously irradiated tissue. Such a tumour is likely to be
relatively radioresistant because of limited blood supply. Re-irradiation of
normal tissue is very likely to result in necrosis.
Field change
Where multiple primary tumours are present, or
if there is extensive premalignant change, surgery is the preferred treatment.
Radiotherapy in these circumstances is unsatisfactory; irradiation of the entire
oral cavity causes severe morbidity and may not prevent subsequent new primary
tumours arising from areas of premalignant change.
Histology
The histology report on a biopsy specimen has
a relatively small influence on choice of treatment. The less common
adenocarcinoma and melanoma are relatively radioresistant, and therefore should
be treated surgically whenever possible. The grade of malignancy of a squamous
carcinoma does not normally influence its management, there being little
evidence
to suggest that a well-differentiated primary should be treated differently from
a poorly differentiated one.
A
possible exception is the verrucous carcinoma, which is the subject of much
controversy. The observation has been made that where large lesions of this
histological type are treated by radiotherapy recurrences appear in some cases
which are of a much more anaplastic pattern than the original primary, and it
has become widely accepted that radiotherapy induces ‘anaplasric
transformation’.
It
seems probable that some verrucous carcinomas already contain foci of more
malignant cells prior to treatment, and that these cells are the ones most
likely to survive after radiotherapy and give rise to recurrence. In practice,
most verrucous carcinomas present at an early stage as superficial
Age
The patient’s age is often quoted as an
important factor which must be taken into account when deciding on a course of
management. With a young patient there is the fear that if radiotherapy is given
it may induce a malignancy in years to come; in fact, this risk is very small
compared with the mortality of the disease itself. Elderly patients tend to be
poor surgical risks, but they also rend to do badly with radiotherapy,
especially external radiotherapy, and often deteriorate and may die as a result
of the debility and poor nutritional status induced by the irradiation.
Chronological age per se should not necessarily be regarded as a
contraindication to surgery.
Carcinoma of
the lip
Carcinoma of the lip most commonly arises at
the vermilion border of the lower lip away from the line of contact with the
upper lip. Only 15 per cent arise from the central third and commissure regions,
and 5 per cent from the upper lip.
Initially
the tumours tend to spread laterally rather than infiltrating deeply;
eventually, if uncontrolled, they can spread into the anterior triangle of the
neck and invade the mandible. Lymph node metastases occur late. Both surgery and
radiotherapy are frequently employed and are highly effective methods of
treatment, each giving cure rates of about 90 per cent.
Up
to one-third of the lower lip can be removed with a
If
more than one-third of the lip is removed, primary closure results in
microstomia. Therefore, for more extensive lip resections it is necessary to
utilise local flaps for reconstruction. For large central defects of the lower
lip, particularly in patients who do not have ageing wrinkled faces, the
‘stepladder’ approach of Johanson gives excellent cosmesis as the
reconstruction advances symmetrical bilateral flaps from the lower third of the
face (Fig. 41.14). This results in a mini facelift’ and the scars are
concealed in the labiomental groove around the chin point. For defects more
laterally, in the lower lip, the upper lip and particularly involving the
commissure,
The
majority of lower lip cancers is caused by ultraviolet radiation and often the
entire vermilion border will show actinic changes. Whenever these changes are
seen a total lip shave would be undertaken in addition to resection of the
primary tumour. The resection is reconstructed either by advancing labial or
buccal mucosal flaps or, if such tissue is inadequate, by the use of a pedicled
anteriorly based tongue flap. After 3 weeks the pedicle is divided and the flap
finally set into the lip.
Carcinoma of
the tongue
Surgery is the treatment of choice for early
lesions suitable for simple intraoral excision, for tumours on the tip of the
tongue and for advanced disease when surgery should be combined with
postoperative radiotherapy. For intermediate-stage disease surgery and
radiotherapy have similar outcomes. When performing surgical excision of less
than one-third of the tongue, formal reconstruction is not
Any
tongue carcinoma exceeding 2 cm in diameter requires at the very least a
hemiglossectomy. Many such tumours will infiltrate deeply between the fibres of
the hyoglossus muscle. Extensive tongue lesions often involve the floor of the
mouth and alveolus. Under any of these circumstances a major resection is
indicated. Access is best via a lip split and mandibulotomy (Fig.
41.16). The
pull-through procedure is not recommended as it is very difficult to achieve
adequate excision in all three dimensions with a limited access. As the
resection opens the submandibular space the resection should include a
dissection of the neck on the same side as the tumour. The type of neck
dissection will depend upon the node status of the patient. A rim resection of
the mandible is indicated if the tumour reaches but does not invade the
alveolus. Such extensive defects require reconstruction with distant flaps. If
the volume of the tongue defect does not exceed two thirds of the original
tongue a radial forearm free flap with microvascular anastomoses gives a good
functional result. For very large volume defects, for total glossectomy or for
deeply infiltrating tumours,
when the resection extends to the hyoid bone,
more bulky flaps are required to fill in the dead space and prevent food
pooling.
A
pectoralis major muscle flap is the best method. Whenever it is possible,
without compromising the resection, at least one of the hypoglossal nerves
should be preserved. If this is done, most patients will eventually relearn to
swallow and will establish reasonable speech.
Carcinoma of
the floor of the mouth
Floor of mouth cancers spread to involve the
under surface of the tongue and the lower alveolus at a relatively early stage.
Therefore, surgical excision will nearly always include partial glossectomy and
marginal resection of the mandible. The resultant defect must always be
reconstructed with either a local or a distant flap. It is unacceptable to
advance the lateral margin of the residual tongue to the buccal mucosa as this
causes very severe difficulties with speech and mastication. Small tumours of
the floor of the mouth that do not show deep infiltration can be treated by
simple excision.
It
is important that a 1-cm margin of normal-appearing mucosa be excised around the
tumour. The resulting defect can either be left to granulate if a carbon dioxide
laser was used for the excision, or fulgurated if diathermy excision was used.
Alternatively, if the defect is large it can be repaired using bilateral
nasolabial flaps tunnelled into the mouth and interdigitated anteriorly. The
submandibular duct should be identified proximally, well clear of the distal
margin of the excision and brought our into the floor of the mouth or lingual
gutter posteriorly.
For
larger lesions and those involving the ventral tongue and/or the alveolus,
surgical access is gained via a midline or lateral (anterior to the mental
foramen) mandibulotomy and lip split. As these extensive tumours have a high
incidence of nodal involvement, the resection is undertaken in continuity with
an ipsilateral neck dissection (Fig. 41.17).
When
there is evidence of gross tumour invasion of the bone resection of the mandible
is mandatory. In order to avoid functional and cosmetic deformity, immediate
primary reconstruction is essential. The choice lies between reconstruction
with vascularised bone, a free corticocancellous graft or an alloplastic system
usually supplemented with cancellous bone mush.
Carcinoma of
the buccal mucosa
Lesions strictly confined to the buccal mucosa
should be excised widely including the underlying buccinator muscle, followed by
a quilted split-skin graft. For more extensive lesions with more complicated
three-dimensional shapes, i.e. lesions extending posteriorly to the retromolar
area, maxillary tuberosity or tonsillar fossa, reconstruction with a free
radial forearm flap is advisable; this adapts very well to such shapes and
remains soft and mobile postoperatively (Fig.
In
situations where a free flap is nor appropriate, alternatives are the buccal
fat pad or the forehead flap. The buccal fat pad has proved to be a useful local
flap for the reconstruction of small intraoral defects up to 3 x 5
cm. This well
vascularised flap can be left raw to
epithelialise spontaneously, and is used to reconstruct maxillary defects, hard
and soft palate defects, and cheek and retromolar defects. For large defects at
these sites its use can be combined with the temporalis muscle flap.
The
use of the forehead flap, an axial flap based on the superficial temporal
artery, was first described by McGregor in 1963. It is a very reliable flap able
to reach most areas within the mouth including the anterior floor of the mouth.
However, it is now rarely used because it results in a very obvious cosmetic
defect at the donor site; it is a two-stage procedure requiring division of the
pedicle at 3 weeks; and it requires the creation of a tunnel, either deep or
superficial, to the zygomatic arch when the flap is needed in the oral cavity.
Carcinoma of
the lower alveolus
In general, surgery is the treatment modality
of choice for all alveolar carcinomas, except for patients unfit for surgery.
Access is achieved via a lip-split approach. Now that the patterns of bone
invasion are better understood, the continuity of the mandible can often be
preserved by performing a marginal resection. If bone invasion is so extensive
that the mandible must be resected in continuity, primary reconstruction
should always be undertaken as the results are always better than those of
delayed reconstruction.
Several
techniques are available for immediate reconstruction of the mandible.
Historically, free corticocancellous grafts harvested from the iliac crest or
rib grafts have been used. Provided there is a good watertight cover to the
graft, results can be very satisfactory, although it is difficult to reconstruct
the chin prominence with this technique. Boyne and Leake have advocated the use
of cancellous bone from
Microvascular
tissue transfer is currently favoured for immediate mandibular reconstruction.
The radial forearm flap with a section of the radius, the compound groin flap
based on the deep circumflex iliac vessels and free fibula flaps have all been
advocated (Fig. 41.20). A problem with the radial flap is that the harvested
bone, although restoring mandibular continuity, is barely adequate for
prosthetic reconstruction.
Soft-tissue
cover for all of these reconstruction techniques is critical. With microvascular
free flaps the associated skin is used. For cancellous bone mush in titanium
trays, and for corticocancellous grafts, the pectoralis major muscle-only flap
is most useful (Fig. 41.21). The pedicle is brought up through the neck and the
flap introduced into the floor of the mouth. The flap is then wrapped around the
bone graft and sutured back on to itself on the labial aspect. Thus, the bone
graft is totally enveloped in well-vascularised soft tissue. The mucosal
resection margins are then sutured to the exposed muscle at their appropriate
sires and the bare muscle allowed to epithelialise spontaneously. Such flaps
withstand immediate postoperative radiotherapy, and the subsequent insertion
of osteointegrated implants has not proved to be a problem.
Carcinoma of
the retromolar trigone
The retromolar trigone is defined as the
anterior surface of the ascending ramus of the mandible. It is roughly
triangular in shape with the base being superior behind the third upper molar
tooth and the apex inferior behind the third lower molar.
tumours
at this site may invade the ascending ramus of the mandible. They may also
spread upwards in soft tissue to involve the pterygomandibular space, which can
be difficult to detect clinically or radiologically.
A
lip split and mandibulotomy are needed to gain access to the retromolar region.
Small defects can often be reconstructed with a masseter or temporalis muscle flap.
Larger defects are best reconstructed with a free radial forearm flap which can
be made to conform very well to the shape of the defect at this site.
Carcinoma of
the hard palate and upper alveolus
These sites are considered together as they
are closely adjacent and both are rare sites of origin of primary squamous
carcinoma. A squamous carcinoma presenting at either of these sites is more
likely to have arisen in the maxillary antrum than in the oral cavity. An
exception is on the Indian subcontinent where carcinoma of the hard palate is
seen in association with reverse smoking. tumours of minor salivary
A
tumour confined to the hard palate, upper alveolus and floor of the antrum can
be resected by conventional partial maxillectomy. A more extensive tumour
confined to the infrastructure of the maxilla requires total maxillectomy. If
the preoperative investigations indicate extension of disease into the pterygoid
space or infratemporal fossa a more extensive procedure is necessary. The
chance of obtaining a cure by surgery alone is small, and postoperative
radiotherapy is essential. A combined anteroposterior or lateral facial
approach is required. If the tumour extends superiorly to involve the dura then
a combined neurosurgical procedure will be required.
Following
a maxillary resection the resulting cavity should be skin grafted to ensure
rapid healing and to prevent contracture of the overlying soft tissues.
The
defect created by surgery will require either reconstruction or a prosthesis.
Various techniques have been described for reconstruction; Obwegeser described
a technique using split ribs. More recently, the temporalis muscle flap has been
advocated. The temporalis muscle flap is a simple technique and has the
advantage that it carries with it its own blood supply. It must be remembered
that if such a reconstruction is to be undertaken subsequently, it is
essential that at the rime of the original maxillectomy the coronoid process of
the mandible is not excised, because if it is resected the blood supply to the
mobilised temporalis muscle will have been compromised and the flap will necrose.
Malignant
melanoma
Oral melanomas are rare. The peak age
incidence is between 40 and 60 years; nearly 50 per cent are on the hard palate
and about 25 per cent are on the upper gingivae. About 30 per cent of melanomas
are preceded by an area of hyperpigmentation, often by many years. Pigmentation
varies from black to brown, while rare nonpigmented melanomas (15
per cent of oral melanomas) are red. Oral melanomas may be flat but are
usually raised or nodular, and asymptomatic initially, but may later become
ulcerated and painful or bleed. Because of their rapid growth, most oral
melanomas are at least 1 cm across, and approximately 50 per cent of patients
have metastases at presentation (Fig. 41.22).
Clinically,
size and rapid growth, particularly if associated with destruction of underlying
bone or presence of metastases, are obvious indicators of a poor outcome.
Microscopically, tumour thickness, measured in millimetres from the granular cell layer
to the deepest identifiable melanocyte (the Breslow thickness), is the main
guide to prognosis. With cutaneous melanomas the 5-year survival rate is
inversely proportional to the Breslow thickness. The poor prognosis of oral
melanomas is probably due to their later detection than more conspicuous skin
tumours.
Other
indicators of poor prognosis are malignant melanocytes in blood vessels and
multiple, or atypical, mitoses. The morphology of the melanocytes or the amount
of the melanin does not appear to affect the outcome.
Once
the diagnosis has been confirmed, the only hope of cure is provided by the
widest possible excision followed by radical radiotherapy. There is no evidence
that chemotherapy is of significant value except for palliation. The over 5-year
survival rate appears to be about 5 per
cent.
Management of
the neck
Patients staged NO. The regional lymph nodes,
although clinically impalpable, sometimes contain occult foci of malignant
cells. It seems reasonable to expect, therefore, that removal or treatment of
regional lymph nodes, even when clinically clear, would improve cure rates.
Alternatively, it can be argued that treatment of the regional nodes in all
cases is unnecessary, as only a minority has metastases in the nodes.
The
arguments expressed in favour of elective block dissection are:
•
the incidence of histologically involved nodes in NO necks varies from 25
to 65 per cent;
•
survival rates are considerably lower in patients who develop node
metastases;
•
the recurrence rare following block dissection is higher in advanced
disease when there is extracapsular spread or multiple nodes;
•
by waiting for clinically detectable disease to develop, many patients
will have a worse prognosis;
•
some patients fail to attend regular follow-up and may not appear again
until nodal metastases are extensive;
•
block dissection of the neck carries negligible mortality and an
acceptable morbidity;
•
retrospective reviews confirm that patients undergoing elective neck
dissection have higher survival rates;
•
failure to control nodal metastases is a frequent cause of death.
•
the incidence of histologically positive nodes in elective neck
dissections exceeds the incidence of subsequent clinical nodal metastases,
suggesting that some microscopic foci are destroyed by the body’s defences;
•
the primary may recur or a second primary develop and metastasise into
the dissected neck, making subsequent management very difficult;
•
elective neck dissection gives no guarantee against recurrence of the tumour
in the neck;
•
block dissection has a considerable morbidity;
•
removal of regional lymph nodes may remove a barrier to the further
spread of disease;
•
there is no prospectively controlled trial to support the argument that
elective neck dissection does improve the prognosis.
On balance, the weight of these arguments
favours prophylactic neck dissection.
As
the submandibular triangle often has to be opened as part of the resection of
the primary, a function sparing elective neck dissection for tumours in the
floor of the mouth and lower alveolar ridge and tongue is advocated. This
dissection, in which structures such as the accessory nerve, internal jugular
vein and sternocleido-mastoid muscle are preserved, can be justified. Further,
a survey showed that of 501 cancers of the oral cavity, 34 per cent of nodes
were found to be positive after elective radical neck dissections. Over 96 per
cent of these histologically positive nodes would have been removed by a supra-omohyoid
dissection.
The
operation should preferably be seen as a staging procedure on which is based the
decision to give radical postoperative radiotherapy. All patients with two or
more positive nodes or extracapsular spread should be treated with postoperative
radiotherapy.
An
alternative approach is elective irradiation of the clinically negative neck,
and indeed there is good evidence that this is of some benefit in preventing
subsequent nodal disease. Certainly, elective irradiation to 40 Gy carries less
morbidity than elective neck dissection.
Patients
staged N1/N2a/N2b. At present, evidence suggests that the treatment of choice
is radical neck dissection, either alone or combined with postoperative
radiotherapy if multiple nodal involvement or extracapsular extension is found
in the resected specimen (Fig. 41.23). In those patients unfit for radical
surgery, radical external beam irradiation is indicated.
Patients
staged N2c. It is uncommon for patients with oral cancer to present with
bilateral nodes. When they do so, there is often a large inoperable primary
tumour which is best treated by external radiation. It therefore seems logical
to treat the neck also by irradiation. Occasionally, particularly in young
patients, bilateral neck dissection can be justified. A full radical neck
dissection is undertaken on the ipsilateral side and the
Patients
staged N3. N3 indicates massive involvement, usually with fixation. Large fixed
nodes are often associated with advanced primary disease with a poor prognosis.
Surgery is not normally advisable: removal of the common or internal carotid
artery with replacement, or extensive resection of the base of the skull,
although technically feasible, is seldom advisable. Treatment is most often by
external radiotherapy. In a few younger patients with resectable primaries, it
is worth rendering a fixed mass in the neck operable by preoperative
radiotherapy.
Provided that follow-up at regular intervals
is rigorously maintained, it should be possible to detect a lymph node
metastasis while it is still relatively small and therefore operable. Fine
needle aspiration cytology is particularly useful in this situation to confirm
that the palpable node is a carcinoma rather than reactive. Whenever positive,
or if there is any doubt, a radical neck dissection is performed, followed by
external irradiation if multiple involved nodes or extracapsular spread are
found.