Lip and mouth cancer
Oral cavity carcinoma represents 30% of all cancers of the head and neck1. We understand carcinomas of the head and neck those that originate in the oral cavity, pharynx, larynx, salivary glands, paranasal sinuses and these represent the sixth most common cause of cancer diagnosis and fourth in men2. Oral cavity carcinoma has an incidence of 17/100.000 men and 11 / 100,000 women in our country2. There are multiple types of malignancies that are encountered in the oral cavity, despite this, more than 90% of carcinomas affecting the oral cavity are squamous cell carcinomas in different degrees of differentiation.
What is the mouth or oral cavity?
The oral cavity is a complex structure, which contributes to a number of functions including talk, facial expression, mouth breathing, chewing and swallowing.
Anatomically, the oral cavity is divided into the following sub locations: upper and lower lips, anterior two thirds of the tongue, floor of the mouth, gingival mucosa, buccal mucosa, retromolar trigone and hard palate. (Figure 1).
Figure 1: Sub locations of the oral cavity.
Each of these anatomical divisions have a different tumor behavior and a local and regional spread different pathway.
Image 1: squamous cell carcinoma of retromolar.
What are the risk factors for this cancer?
Smoke and alcohol are the main risk factors for developing this neoplasm. These two factors behave as carcinogens by themselves but together develop a synergic mechanism3.
Human Papillomavirus Infection (HPV) has been linked very intensively with oropharynx carcinoma, finding association in 35-40% of cases of this tumor4, it has also been associated in some cases with oral5 cavity carcinoma.
Exposure to ultraviolet radiation has been associated mainly with the labial location of such carcinoma. Other factors have been associated as work related to the steel industry, poor dental hygiene, chronic mechanical irritation, recurrent infections and dietary factors related primarily as protein and vitamins6 deficits.
In recent years there have been multiple studies that attempt to assess the genetic alterations that give rise to individual susceptibility to these cancers, apparently there is a subgroup of patients not on risk factors that would suffer from these tumors because of these genetic alterations7.
How does cancer develop?
Oral cavity carcinoma develops through a series of molecular changes that are reflected in the histopathological analysis from mild, moderate or severe dysplasia and carcinoma in situ or subsequently invasor.
The lesion clinically appears as a whitish area we call leukoplakia, usually these lesions are areas of hyperkeratosis that may have or may not have cellular atypia. Lesions associated cellular atypia are most often manifested like Erythroplasia.
A study of pathological lesions of leukoplakia review found that 80% of oral leukoplakia showed no epithelial dysplasia, mild dysplasia or moderate 12.2%, severe or carcinoma in situ 4.5% and invasive carcinoma was found only in 3.1% of cases8.
Infiltrating carcinoma is able to grow locally, the direction of growth will depend on the initial location of the tumor, mainly regionally to lymph nodes in the neck in a pattern according to the primary location of the initial tumor9.
How is it diagnosed?
First, after the completion of the medical record, a scan must be performed for the local pathology assessment. Here, as in all ENT tract carcinomas, a ENT complete exploration must be performed looking for synchronous tumors and assessment of the possible presence of cervical tumors suggestive of regional metastases.
While biopsy is obtained imaging tests should be performed.
Computed tomography (CT) and Magnetic Resonance Imaging (MRI) provide similar efficacy in the evaluation of initial nodal staging of the disease, while for local tumor assessment, MRI appears to provide advantages especially in the evaluation of the invasion muscular, nervous and in cases of tumor extension into the oropharynx and in cases of dental artifacts in the TC10.
If mandibular invasion is suspected the assessment of it is a controversial issue.
CT provides a positive predictive value (PPV) of 90% for bone invasion but the negative predictive value (NPV) only reaches 60% in locations like the trine retromolar11. Some authors advocate the use of Dentascan with results reaching 87% of VPP and 92% in the VPN12.
MRI is useful for the assessment of the possible invasion of the medullary bone but for the cortical invasion has no advantages.
Another exploration proposed for this purpose has been the SPECT has demonstrated very good sensitivity (97%) but a limited specificity (65%)13. The test provides the best results is the intraoperative analysis of the possible existence of periosteum infiltration, but has the disadvantage that it is a test done at the time of surgery.
The recommendation in cases that raise doubts to achieve a good presurgical planning would be the combination of two imaging; one that provides greater sensitivity and other with greater specificity.
Una vez realizada la valoración clínica del tumor se obtendrá un estadiaje del mismo basada en la extensión anatómica del mismo a nivel del tumor inicial, afectación regional y/o a distancia basa en el sistema TNM de estadiaje de la Unión Internacional contra el cancer14
Esta clasificación nos aporta la principal herramienta para decidir el tratamiento a aplicar así como para aportar un pronóstico al paciente. Este método no tiene en cuenta factores no anatómicos que pueden influir en el diferente comportamiento de estos tumores15.
Hoy en día se han demostrado múltiples dianas moleculares que pueden influir en la evolución de estos pacientes, entre ellos uno de los más importantes el VPH principalmente en carcinomas de oro-faringe, probablemente en el futuro estos se emplearan con este propósito.
how is it treated?
In early stages (I-II) of the disease will attempt to make a mono-therapy treatment based on surgery or radiation therapy either by external irradiation or interstitial application (brachytherapy). The choice of it will be based on the patient’s wishes as well as the effects of surgery versus radiotherapy. In general the side effects of radiotherapy (xerostomia, dysphagia, radionecrosis) in this location as well as the duration of treatment (6-7 weeks) make, if technically and functionally possible surgical initial treatment arises.
In advanced stages are usually candidates for multimodal therapy based on surgical resection followed by radiation therapy, the use of radiotherapy prior to surgery is reserved for cases selected as this combination has been associated with a higher rate of surgical complications17. In this location, unlike other head and neck, induction chemotherapy has not shown good results, while chemotherapy associated with radiotherapy after surgery has a higher survival rate at 5 years in these patients18.
Chemo radiotherapy as first choice is accepted in those cases where surgical resection involves a total glossectomy.
Surgery in the oral cavity
For surgical management of these tumours can be used different approaches, this decision will influence the location of the original tumour, as well as its size, infiltration depth and proximity and / or infiltration of the mandible.
Based on these factors its possible to make a transoral approach for those previous injuries floor of the mouth and mobile tongue. Limited to lip injuries will be subject to an external approach. Lesions reach the back of the oral cavity or oropharynx may require a mandibulotomy approach. The approach using lower cheek flap is useful to avoid mandibulotomy in tumours due to its proximity to the jaw cannot use a trans oral resection. The approach using “flap visor” avoids the incision of the lower lip giving good exposure to all the anterior floor of the mouth.
The upper cheek flap is useful for lesions involving the maxilla without allowing transoral excision19
Figure 3: Possible surgical approaches for resection of tumors in the oral cavity except the lips19.
Those tumours that infiltrate the jaw should be treated by resection of the mandibular bone. It is now accepted that a marginal mandibulectomy provides similar results to a hemimandibulectomy for those cases where the mandibular infiltration does not reach the spinal cortex. If invasion of the medullary cortex is found a mandibulectomy must be done in the surgical treatment of these tumors.
Sometimes performing a marginal mandibulectomy, in cases where invasion mandibular not suspected, to obtain adequate surgical margin, or proper exposure may be necessary. Today, the mandibulectomy is not considered appropriate to improve surgical exposure and to maintain continuity between a neck dissection and local tumor if there is no mandibular invasion (type Resection “command”) because there are no nodes crossing the jaw20.
The reconstruction of surgical defects can be done by primary closure or the use of local, regional or distant flaps from other parts of our body through techniques of reconstructive microsurgery. These techniques are the basis to perform transplants of tissue from other parts of the body towards the area where the defect exists and they can be attached blood vessels that nourish the graft and nerves so that it can continue to function and / or sensitivity.
Image 2: Right mouth floor completely rebuilt by a microanastomosado forearm flap.
Image 3: Design forearm flap.
Management of cervical lymph nodes
Management in those patients without evidence of regional metastasis after diagnosis process is discussed. The existence of about 30% of occult metastases in cases initially staged as N0 is accepted. The lymphatic drainage of the oral cavity follows a direction toward the cervical areas21 well described.
The current treatment for N0 cases is elective neck dissection of the cervical areas I-II and III, but now is expanding the use of sentinel node localization. This is to locate the node or nodes with an increased risk of metastasis and removal for histopathological analysis, if it does not contain metastases is not carried out neck dissection.
This technique has shown a rate of cervical recurrence of 5% in those cases where the sentinel node does not show invasion tumoral22 is for this reason that currently are underway multiple multicentre studies and possibly, in the near future, it will be the technique of choice for the diagnosis and therapeutic management of these patients neck.
In those cases where diagnostic tests detect the presence of lymph node metastasis and the patient is undergoing surgery should be performed neck dissection based on the clinical and surgical findings.
If the patient receives radiotherapy on local tumour as a first move, it should also apply radiotherapy on nodal areas when necessary.