From OncoLog, November-December 2011, Vol. 56, Nos. 11-12
Transoral Laser Microsurgery for Laryngeal and Oropharyngeal Tumors
By Sarah Bronson
A minimally invasive surgery for treating cancers of the larynx and oropharynx has cure rates similar to those of open surgery and radiation therapy in selected patients.
For much of the past century, cancers of the larynx and pharynx have required radical surgical approaches such as total laryngectomy, which results in a stoma, or vertical partial laryngectomy, which preserves part of the functioning larynx but results in severe dysphonia.
As a result, more than 20 years ago, the standard treatment for these lesions shifted to radiation therapy, which is sometimes combined with chemotherapy. Compared with open surgery, radiation therapy may offer patients a better chance to preserve native speech and swallowing.
Today, transoral laser microsurgery can achieve a cure rate similar to that of radiation therapy while offering better organ preservation and fewer adverse sequelae for selected patients with early- or intermediate-stage laryngeal or oropharyngeal cancers that are amenable to resection.
Many of the patients selected for transoral laser microsurgery have stage I or II laryngeal cancer. Because the larynx is integral to speech, swallowing, and respiration, the effectiveness and aggressiveness of therapy can greatly affect long-term quality of life and options for future therapies. For patients with early-stage disease, transoral laser microsurgery can provide both curative treatment and organ preservation.
In traditional open surgery for laryngeal cancer, the surgeon resects not only the larynx and surrounding tissues but also the involved vocal cords and supporting structures such as cartilage, which must then be reconstructed.
Open surgery is associated with pain, loss of normal function, and long recovery times. Its potential to adversely affect speech, breathing, and swallowing is a major concern in patients with poor pulmonary function.
In contrast to open surgery, in transoral laser microsurgery, the surgeon accesses the tumor through the mouth with the aid of an endoscope. “You’re not disassembling the neck,” said Chris Holsinger, M.D., an associate professor in the Department of Head and Neck Surgery at The University of Texas MD Anderson Cancer Center. “You’re going through the mouth as a natural orifice and causing as little collateral damage as possible.”
A transoral approach gives the surgeon direct access to and magnified, high-resolution views of laryngeal tumors without the need for external incisions. After the patient has been put under general anesthesia and intubated, an endoscope is inserted through the patient’s mouth and pharynx and centered over the tumor. An operative microscope is then aligned with the endoscope, and a carbon dioxide laser is coupled to the microscope so that the view through the microscope aligns and moves in accordance with the path of the laser beam. In many patients, the tumor can be reached with a line-of-sight beam; in patients with more out-of-the-way tumors, a highly reflective optical fiber can be used to bend the beam and increase the variety of possible cutting angles.
The goal of transoral laser microsurgery is to resect laryngeal and oropharyngeal tumors with minimal damage to normal tissues and maximal preservation of organ function. Therefore, the tumor is resected with as narrow a surgical margin as possible.
Halsted’s principle of removing a tumor en bloc does not always apply in transoral laser microscopy. In fact, dividing the tumor and removing it one piece at a time is not only possible but also often necessary for the complete excision of some larger tumors. Dividing the tumor also enables the surgeon to better assess how far the tumor extends into the surrounding tissue; some “iceberg” lesions may invade to depths that cannot be identified with preoperative laryngoscopy. Also, dividing the tumor is sometimes necessary if the whole tumor is too large to be retracted and ultimately removed by the endoscope.
The extent of normal tissue conservation warranted in patients with head and neck cancers requires the precision of a laser, especially when the surgical site is in the confined space of the upper aerodigestive tract. The laser beam vaporizes a small number of cells at a time and cauterizes adjacent surfaces. The standard carbon dioxide laser’s high coefficient of absorption in water limits the beam’s penetration, allowing precision in cutting soft tissue with minimal collateral thermal damage to surrounding nerves.
A single laser beam can serve as many different tools. The shape, size, and depth of the laser’s penetration can be configured to meet different needs as they arise during surgery. Broadening the beam—retaining the same energy over a larger area—creates a tool for coagulating small blood vessels; narrowing the beam to increase its focus and power creates a cutting tool. Multiple passes of the laser can be made in quick succession to cut through multiple layers of tissue in one location, or each pass can be made independently to cut through smaller amounts of tissue.
Because the heat of the laser cauterizes the edges of the wound the laser creates, no further action is needed to close or cover the area after the tumor has been removed; the wound heals by secondary intention. In fact, tissue heals more quickly after laser surgery than after robotic or traditional open surgery. Transoral laser microsurgery is associated with postoperative complication rates well below 5%.
Often, patients spend only a day or two in the hospital and resume their normal activities within a week. Patients with stage III or IV cancers, some of whom receive adjuvant radiation therapy, generally leave the hospital less than a week after undergoing transoral laser microsurgery.
Outcomes of different modalities
Radiation therapy is a well-established first-line therapy for early-stage laryngeal cancer and has high cure rates. Furthermore, radiation therapy with or without chemotherapy can preserve the structure and function of the larynx while delivering curative treatment in many patients with early- or late-stage laryngeal cancer.
However, these aggressive treatments often cause adverse effects, such as soft-tissue fibrosis, dry mouth, swallowing problems, or loss of sense of taste. Diminished sensory function of the laryngopharynx may predispose patients to aspiration and subsequent pneumonia.
“In selected patients—especially younger patients, who are at higher risk for the cumulative long-term side effects of radiation therapy—transoral laser surgery can spare the need for radiation and eliminate these side effects,” Dr. Holsinger said.
Transoral laser microsurgery for early laryngeal cancer yields treatment outcomes similar to those of radiation therapy and achieves a level of tumor control approximately equal to that of radiation or chemoradiation therapy. For example, the survival rates of patients with T2 cancers treated with transoral laser microsurgery tend to be similar to those of patients with T2 cancers treated with radiation therapy.
Dr. Holsinger emphasized that radiation therapy plays a critical role in the treatment of head and neck cancers; for many patients, particularly those whose tumors are no longer at early stages, radiation therapy is the most effective option. However, the routine use of radiation therapy as an initial treatment may limit its use later as a treatment option for persistent, recurrent, or second primary disease. Radiation therapy generally cannot be repeated for curative purposes, so if the tumor recurs, radical surgery will likely be needed. For patients undergoing salvage surgery, previous radiation therapy or chemotherapy can also increase postoperative complications and limit options for conservation surgery.
In contrast, transoral laser microsurgery does not preclude additional therapy of any type. In fact, postoperative adjuvant radiation therapy may be required in patients with intermediate- or advanced-stage cancer.
Transoral laser microsurgery is an effective curative treatment for early-stage laryngeal cancer. The technique is an established modality for early T1 cancers and is considered safe for T2 cancers.
Transoral laser microsurgery can sometimes be used to remove advanced laryngeal cancer while preserving speech and swallowing functions; however, its effectiveness as a treatment for advanced cancers is not established and warrants further study. Transoral laser microsurgery can also be used as salvage surgery in some patients with recurrent laryngeal cancer.
To determine whether transoral laser microsurgery will be effective, surgeons examine the affected tissues of the laryngopharynx by palpation, endoscopy, computed tomography, and/or videostroboscopy to evaluate the extent of the tumor’s invasion and the potential for cure by conservation surgery. Videostroboscopy in particular provides dynamic images that show laryngeal function in detail. Still, the tumor and surrounding tissues are best visualized during surgery, and the surgeon must sometimes adapt the procedure to unexpected findings.
Some large, invasive tumors in the upper aerodigestive tract cannot be cured with transoral laser microsurgery; these cases necessitate radiation therapy. Another contraindication to transoral laser microsurgery is the inability of the surgeon to visualize the tumor or expose the site of the tumor for surgery because of conditions such as trismus, a large tongue base, or prominent dentition.
Transoral laser microsurgery can be an effective alternative to radiation therapy and other more invasive modalities in cancers of the laryngopharynx for which aggressive treatment is not indicated. The stage and depth of invasion of the cancer, the age and treatment history of the patient, and even the amount of free time the patient has can influence the decision.
“If transoral laser surgery can preserve function and achieve tumor control, then this innovative approach should be considered,” Dr. Holsinger said.
For more information, contact Dr. Chris Holsinger at 713-792-4726.
For a more comprehensive discussion of radiation therapy and surgery in patients with laryngeal tumors, please see: Hosemann S. Compass: Early-Stage Laryngeal Cancer. OncoLog. January 2009.