Updated: May 2003
Carcinoma in situ
Surgical or laser excision are used for localized lesions. A gold seed implant or radioactive iridium implant could be also employed in selected cases. External beam irradiation is occasionally used for widespread lesions that cannot be controlled by other means.
Most of these cancers are squamous cell carcinomas and the primary treatment of curable disease is surgical resection and/or radiation therapy. Adenocarcinomas of minor salivary gland origin, connective tissue tumours and mucosal melanomas are best treated with primary surgery, post-operative (rarely pre-operative) radiotherapy may be indicated depending on the individual situation.
The anatomical sites of the oral cavity are: floor of mouth, lower alveolus, buccal mucosa, upper alveolus, hard palate, and anterior two thirds of the tongue. careful clinical and radiological assessment is essential to determine the extent of these tumours. When assessing tumours of the upper alveolus, gingiva and hard palate, it is important to rule out the possibility that they represent downward extension of a primary tumour of the nose or paranasal sinuses.
The following general principles hold for all oral tumours, important points relating to specific anatomic subsites are described thereafter.
Clinically "early tumours" (less than 4 cm)
T1 T2 NO N1 MO
Treatment of the primary tumour may be either excision or radiotherapy. Surgery is usually recommended when the tumour can be removed with a good functional result, radiotherapy is used in preference to more major resections and reconstruction. The radiotherapeutic options include both radioactive implants and external beam radiotherapy. Implants treat only the primary tumour whereas external beam treatment may include both the primary tumour and adjacent lymph nodes.
Gold seed implant
Suitable for very superficial lesions confined to the floor of the mouth or tongue. Tumours that lie very close to the mandible are not usually suitable for a radioactive implant.
The small radioactive gold "seeds" or "pellets" are implanted under local or general anesthesia and remain in the tissues permanently. The patient is admitted to a shielded hospital room for one or two days until most of the radioactivity has decayed. Within 2 months the seeds have lost their remaining radioactivity and are effectively inert.
Radioactive Iridium Implant
Used alone to treat more invasive but localised tumours without evidence of nodal metastasis. In some cases an implant is used in combination with external beam treatment to boost the dose to the site of bulky disease.
Under general anesthesia, thin plastic catheters are placed in and around the cancer. The patient is placed alone in a shielded room and then Iridium-192 is loaded into the catheters either manually or by remote control.
Treatment duration is usually 3 to 7 days, following which the plastic catheters are removed under mild sedation.
External Beam Irradiation
This is used for lesions which are not felt to be suitable for an implant such as floor of mouth cancers that have extended marginally onto the alveolar ridge or when it is desirable to treat the regional lymph nodes. The standard course of treatment for early cancers usually lasts for 5 weeks and is given on an outpatient basis.
Locally Advanced Lesions (more than 4 cm or with bone invasion)
T3 T4 N0 N1 N2 N3 M0
For these advanced lesions the primary curative treatment is usually a combination of surgery and radiation. The decision for each individual patient depends on the specific clinical situation, the patient's overall general condition and the extent of the disease. Bone involvement and/or the presence of regional lymph node metastases may indicate primary surgical treatment. Patients who are unfit for surgery or deemed unresectable are usually treated by radiotherapy. If the patient is still suitable for radical treatment, accelerated radiotherapy with twice daily treatment or radiation may be used with concurrent chemotherapy.
Major resections of advanced oral cavity tumours require the specialized skills of individuals with experience in head and neck surgical oncology including primary reconstructive techniques. The surgical emphasis is to cure the cancer and obtain the best functional and cosmetic results