Oral cavity cancer is usually treated with surgery, sometimes followed by adjuvant treatment with radiation or chemotherapy. The most common type of malignancy in the mouth is squamous cell carcinoma, which is a type of epithelial cancer. The most significant risk factors associated with oral cancer are tobacco exposure, alcohol exposure, prior radiation exposure, poor oral hygiene, chronic inflammation, and viral exposure. Oral lesions can have a variety of appearances or symptoms. A lesion is recognized as an area of altered color or texture. Alternatively, as some places in the mouth are difficult to visualize, a patient may present due to bothersome symptoms such as pain.
If the lesion is an invasive cancer, then a surgery will be planned, which will be designed to remove the lesion completely with a wide rim of normal tissue buffer surrounding the invasive cancer. Imaging, either a CT with contrast or an MRI with contrast, is very important in this setting for guiding the planned surgical excision. In addition, this helps assess the state of the neck lymph nodes, which are at risk for metastatic disease from an oral cancer. A PET/CT might also be recommended in addition to the other types of imaging, as this uses the relative metabolic state of body tissues to help identify locations concerning for cancer presence in the whole body. There are two often misunderstood facts about PET/CT results, which is that it is not sensitive for identifying
early or small metastases of cancer (ie any metastasis will have grown to a size between 6-8mm to be reliably identified with PET), and it is not specific for identifying cancer (ie an area of uptake could represent malignancy, with alternative explanations being inflammation/infection, or normal physiologic activity).
Typically, a surgery is recommended which includes several different components: a) the excision of the oral cancer; b) a removal of lymph nodes from the neck; c) and a reconstruction of the surgical site. Other procedural components as ancillaries may also be necessary, depending on the specifics of the situation (such as placing a feeding tube for nutrition, or a tracheostomy for airway protection).
The oral cancer excision is approached in a manner specific to the unique situation of each patient, depending on the exact location of the lesion and the specific circumstances. There are some common procedural designations, such as ‘partial glossectomy’, or ‘hemiglossectomy’, or ‘mandibulectomy’, or ‘buccal resection’, or ‘maxillectomy’, etc, though these are fairly general descriptions for categorization purposes, and the details of what actually is done is tailored to the unique lesion under evaluation.
The most important detail of surgical treatment of oral cancer is that final negative pathologic margin is
obtained. This means that the pathologist evaluates the tissue that is removed, and can confirm under the microscope that there is a normal rim of tissue around the excised cancer. Ideally, the main tumor resection specimen is removed in one piece with this completely intact rim of normal tissue around it — this gives the best prediction that the cancer is fully removed and will not return. If the specimen is fragmented or removed piecemeal, or the initial excision attempt does not have clear margins, and further tissue is removed to try to clear the margin, the chances of the cancer not having been completely removed and returning is unfortunately higher. Sometimes, this is because of the behavior of the cancer, in more extensively infiltrating the tissue or invading along structures that are difficult to track and clear. Though, to ensure it is not a technical issue with the surgery not having an adequate access or approach to the cancer, often steps are recommended to increase the ability to visualize and assess the tumor adequately. This may include removing adjacent dentition, or bone of the alveolus, or creating a controlled cut in the jaw bone and chin to open the oral aperture as widely as possible. These steps do result in some added side effects, though are generally fairly well tolerated and acceptable in the long term.
If the jaw bone is invaded by the cancer, then it is removed with wide margins as well. If the full thickness of the jaw bone is resected, then this will typically be reconstructed with bone transferred from some other site in the body (fibula or scapula bone), with a microvascular free tissue transfer technique.
The neck lymph nodes at risk for metastasis from the cancer are removed, in a procedure called a neck dissection. This is a very common procedure in head and neck surgery, as it is employed in the majority of tumor types and sites in the head and neck. The neck lymph nodes are categorized by anatomic location into levels, and for a site such as the oral cavity, there are specific levels considered to be at risk for metastases: along the lower border of the mandible, and along the internal jugular vein descending towards the collarbone.
The reconstruction of the oral wound is the third aspect of the surgery. Sometimes, the wound in the mouth is superficial enough, with a healthy wound bed, that it will heal on its own without any further intervention. This is known as secondary intention healing. A site such as the tongue can heal by secondary intention very effectively. This does not mean that the tongue muscle regenerates; instead, the wound edges contract and close towards each other and seal completely. The timing can vary, depending on the size and circumstances, though this process would typically occur over many weeks. A downside is that contraction and scarring occurs, which potentially could be problematic and restrictive in some locations in the mouth. So sometimes a skin graft or artificial dermis is placed on the wound bed, to speed the healing and try to limit the degree of scar retraction. In the mouth and depending on the location and amount of motion, skin grafts aren’t always highly dependable or successful. For more reliable wound coverage when the issue is more critical for long term success, a transfer of vascularized tissue is needed. This is categorized as either a pedicle flap, which is essentially elevated on a dependable set of blood vessels and rotated into place inside the mouth; or as a
free flap, which is harvested from a remote site in the body, with a dependable vascular pedicle supplying the tissue, and the tissue is transferred to the mouth and neck and the blood vessels are attached with suture under a microscope to maintain blood flow through the transferred flap tissue. Either technique has high reliability and effectiveness, and choice usually is determined based on particular unique details of each situation. Types of pedicle flaps in common use include the submental, supraclavicular, pectoralis, or buccal. Common free flaps include the radial forearm, anterolateral thigh, fibula, scapula, or lateral arm.
The results from surgery, including information from the pathology report including margin status, perineural spread, lymph node metastasis, and other details, will lead to a recommendation for any adjuvant treatment following recovery from surgery. Before starting adjuvant treatment, healing from the surgery will be done. This is during the 6 weeks following surgery. Swallowing ability and discomfort is improving, tongue movement is improving, speech is typically close to normal. Issues can arise which delay recovery, including infection or fistula. These are managed with conservative treatments including antibiotics and wound care. If a tracheostomy was needed, this is most often being removed 1 to 2 weeks after surgery. Therapists, including speech pathologists and physical therapists, are typically involved to help with functional recovery.
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