Transoral Laser Microresection of Advanced Laryngeal Tumors

Terms and Definitions

Transoral laser microsurgery (TLM) is a surgical treatment strategy for primary cancers of the mouth, pharynx, and larynx. In TLM, the instrument of excision is generally a carbon dioxide (CO ₂ ) laser beam, an operating microscope imparts the perspective, and the natural passageways of the upper aerodigestive system provide the access.

Two features distinguish TLM from open surgery : healing is allowed to occur by secondary intention and the tumor block can be subdivided into manageable units by the laser (in situ).

TLM is clearly a conservation strategy, but it is not a reconstructive one. “Piecemeal” removal is a distinguishing feature of TLM—and a key source of controversy. Tumor transection endows important diagnostic dimensions to TLM, and magnification exploits the difference in visual appearance between normal tissue and cancer.

Safe TLM requires two conditions: adequate exposure through the mouth and a tangible specimen.

TLM is an excision, not vaporization. A specimen is the basis of meaningful frozen section margins. Individual specimens may be small, but, in aggregate, the resected tissue volume parallels that of an open operation.

In many ways, TLM is a misleading name. TLM is not totally transoral—open surgery is still required for nodes in the neck. TLM is not entirely laser, either—it depends on endoscopic cautery, vascular clipping, and occasionally blunt and sharp dissection. Finally, TLM is not exclusively surgical—radiotherapy may be offered (for neck indications, but never to finesse margins).

The aim of TLM is to improve cure and function through patient selection and technical excellence. The goal is the cure rate of open surgery and the functional promise of a tissue-conserving treatment like radiotherapy, all with less morbidity, at lower cost.

“Advanced” (as in “advanced laryngeal tumors”) is a confusing term. In the context of laser surgery, it once meant any tumor larger than T1a glottic. In traditional discussions, it used to mean cancer with a fixed cord. The staging system suggests a different connotation—positive neck nodes. What is clear is that laryngeal cancer is not one disease. It is many different diseases. And unless we digress and clarify the descriptors of the different laryngeal cancers, all discussions of treatment are ambiguous. The answer to the question, “Does an advanced case qualify for TLM?” is “It depends. What do you mean by advanced?” Let's look at the classifications.

Is it cancer? Laser surgery manages everything along the histologic spectrum, but this chapter only relates to the worst actor, invasive squamous cell carcinoma. The Ljubljana taxonomy is probably the closest thing we have to an internationally accepted classification of epithelial hyperplastic laryngeal lesions (EHLL). For the most benign, “simple hyperplasia,” acanthosis predominates. “Abnormal hyperplasia” is next, and basal proliferation is the hallmark. “Atypical hyperplasia” features dysplasia and atypia. Fourth is carcinoma in situ (CIS), cytologic neoplasia on an intact basement membrane. All these can be laser resected, but TLM is a higher strategy for a higher challenge, group five neoplasia with subepithelial penetration (i.e., invasive squamous cell cancer).

Is it TLM? An excellent classification for laser cordectomies has been developed by the European Laryngological Society. It names five types: subepithelial, subligamental, transmuscular, total, and extended cordectomy ( Fig. 107.1 ). The first three are elegant one-piece excisional biopsies, and a laser may be used on them. TLM (and the strategy of depth determination) comes into play for the last two.

What site? Before multidisciplinary committees imposed a theoretic anatomic classification (glottic, supraglottic, and subglottic) on laryngeal cancer, surgeons included clinical behavior in the sorting system. For 50 years, laryngeal cancer was “intrinsic” or “extrinsic.” Intrinsic was “interior region” cancer, primarily glottic in origin, and slow growing, and its nodes were generally late. TLM treats most of these, but not all. Extrinsic cancer was more supraglottic, originating around the laryngeal opening or its pharyngeal surface. It had a higher rate of metastases and was more lethal. TLM treats the local disease, but not the metastases.

Currently, the official categories are glottic, supraglottic, and subglottic, whereas “transglottic” is used to describe tumors that span the ventricle. However, in the anterior larynx, glottic and subglottic cancers behave similarly. Subglottic cancer often turns out to be glottic, with descent. The height of the glottis is controversial (5 mm high, 10 mm high) or excluded posteriorly (sparing the posterior commissure). None of the sites is off-limits to TLM.

In discussing local extent, clinicians often reduce their spoken references to “early” and “advanced” laryngeal cancer, the traditional dividing line being vocal cord motion. In these terms, TLM is primarily an “early” cancer treatment, as opposed to the “advanced” group.

The tumor, node, metastasis (TNM) staging system uses TX, Tis, T1 (a and b in the glottis), T2, T3, T4a, and T4b to define a local tumor, expanding 3 regions to 18 “extents.” And this is just for the local disease (T). Nodes multiply the possibilities by 7. Metastases multiply the possibilities by 3, for more than 300 possibilities. Some are suitable for TLM. Some are not. No one knows where we should place the dividing line, or where advanced should start (or end). The staging system does encourage a summary format, stage I, stage II, stage III, and stage IV, but the neck dominates this classification. If the neck is positive, everything is stage III or IV (advanced), even if the primary is miniscule.

The staging of laryngeal cancer is not linked to any particular therapy and has significant limitations. TNM staging leaves out historical factors (age, previous treatments, habits, work, duration of and number of symptoms, literacy, religious beliefs, distance from treatment facility, etc.) and leaves out comorbidities. Both symptom severity scores and comorbidity scales have been shown to improve the accuracy of TLM. TNM also ignores complex patient factors (e.g., exophytic vs. endophytic, keratinized vs. ulcerated, stridor, obesity vs. cachexia, forced expiratory volume, ejection fraction, hemoglobin, protein levels, blood sugar, liver function tests). These and other limitations of TNM staging pose challenges to the treating physician.

This leaves the doctor with the problem of how to interpret the term “advanced” in the context of TLM. It makes little sense to link advanced to a higher TNM stage (III or IV) if patients with T1 and T2 local cancers will be included (all that is required to make a T2 cancer “stage III” is for someone to feel a node in the neck). For example, the 2002 American Joint Committee on Cancer (AJCC) TNM staging of larynx cancer states that stage III includes T1, T2, or T3 N1 (or T3 N0), where N1 is a single node smaller than 3 cm. The AJCC also lists stage IVA to include T1, T2, T3, or T4a N2 (or T4a N1 or N2), where N2a is a node between 3 and 6 cm in size, on the same side; N2b is multiple nodes smaller than 6 cm, on the same side; and N2c is bilateral or contralateral nodes smaller than 6 cm in size.

This chapter is primarily about the treatment of the local diseases by TLM. Therefore we need to classify local diseases and to help distinguish those for which TLM is an option and those for which it is not. In this chapter, we therefore describe extent of disease based on local invasion, not based on nodal status, unless otherwise indicated.

Five Types of Local Laryngeal Cancer

From the surgeon's standpoint, local laryngeal cancer comes in five different “flavors,” each one more damaging (to function) and more difficult to cure. Severity relates to what stock local excision would be required for complete removal. What would that impose on the patient, in terms of voice, swallow, and nasal breathing? This does not indicate the treatment is surgery. It does ensure that the appropriate local option for surgery is identified, especially to the patient, when the selection among various modalities is made. Each flavor can, thus, be defined by one of five classic excisions, which ascend in severity from laryngoscopic biopsy to total laryngectomy (TL). Each excision removes a customary block, from one nodule to the whole larynx and its coverings, and each has a formal technique. We have a published record for each of local control rates from 98% to 80%. The expected functional outcome ranges from normal voice, swallow, and breathing down to tracheoesophageal puncture (TEP) voice and stomal breathing. Each of these five categories can be named as follows: very early, early, intermediate, advanced, and very advanced. We use this terminology to describe local extent, unless otherwise indicated.

• 1

  Very Early

  Exophytic midcordal T1a carcinoma. Encompassed by transoral excisional biopsy removal via resection or ablation. Includes one-piece subepithelial cordectomy subligamental partial cordectomy, and midcordal transmuscular cordectomy.

• 2

  Early

  Two subtypes, glottic and supraglottic.

  • a

    Early Glottic

    • T1a, T1b, and T2a true cord carcinoma whose formal external excision would be a vertical partial laryngectomy (VPL) or hemilaryngectomy. The European Laryngological Society's total cordectomy and extended cordectomy concepts probably fit here.

  • b

    Early Supraglottic

    • T1 supraglottic carcinoma fitting within a supraglottic laryngectomy block.

• 3

  Intermediate

  Laryngeal cancer that fits within a supracricoid partial laryngectomy (SCPL) block. Thus T2 glottic carcinoma (T2 by spread to the supraglottis), T3 glottic (T3 by thyroid cartilage erosion from the anterior commissure—mobility is preserved), T2 supraglottic (T2 by descent to involve the vocal cords), or T3 supraglottic cancer (if T3 by involvement of the preepiglottic space [PES]).

• 4

  Advanced

  T3 glottic carcinoma (T3 by unilateral cord fixation and invasion of the paraglottic space or the thyroid ala) is the prototype because it is lateralized and fits within a near-total laryngectomy (NTL). Lateralized invasive T2b glottic carcinoma qualifies if the T2b is by impaired mobility of one vocal cord. Also, advanced glottic carcinoma includes T2 supraglottic carcinoma, where T2 means involvement of the vallecula or the medial pyriform wall, and T3 supraglottic carcinoma, where T3 means unilateral cord fixation with invasion of the paraglottic space or the thyroid ala.

• 5

  Very Advanced

  Bilateral anterior T3 glottic carcinoma invading both ventricles, bilateral posterior T3 supraglottic cancer invading the postcricoid region, or T4a glottic or supraglottic carcinoma, which means the cancer has invaded into adjacent structures outside the larynx—the strap muscles, the thyroid gland, the tongue beyond the immediate base, the trachea, or the esophagus. The minimum excision these cancers would require is at least a wide field TL (T4b is incurable by surgery). T4b means gross distant extension. But this is virtually unheard of in cancers with no prior treatment. Examples include direct extension into the prevertebral space or the mediastinal structures or encasing the carotid.

Now we can examine TLM in the context of the clinical severity of the local disease. Others can judge the use and validity of the approximate term locally advanced.

Acronyms

• CHEP Cricohyoidoepiglottopexy. Reconstruction for SCPL.

• CHP Cricohyoidopexy. Reconstruction for SCPL.

• HSL Horizontal supraglottic laryngectomy.

• KTP Potassium titanyl phosphate

• NTL Near-total laryngectomy. Frontoanterior VPL with epiglottoplasty, SCPL, and NTL have at various times all been called subtotal laryngectomies.

• PES Preepiglottic space.

• SCPL Supracricoid partial laryngectomy. Frontoanterior VPL with epiglottoplasty, SCPL, and NTL have at various times all been called subtotal laryngectomies.

• TLM Transoral laser microsurgery.

• TEP Tracheoesophageal puncture, tracheoesophageal prosthesis.

• VPL Vertical partial laryngectomy. Includes the vertical frontoanterior and frontolateral partial laryngectomies, and hemilaryngectomy.

• TL Total laryngectomy

Laser Surgery and Transoral Laser Microsurgery in the Treatment of Locally Early, Intermediate, and Advanced Cancers

Laser surgery is not new in larynx cancer. Davis and colleagues; Jako and colleagues; Strong; and Vaughan and associates all treated selected tumors during the 1970s and early 1980s.

Through the 1980s and 1990s, Motta and others and Steiner pioneered a new concept: tumor transection in situ. Consider the implications. If infiltrative cancer could be safely resected in pieces, tumor depth could be determined in situ. Incremental resection would become possible—as in Mohs chemosurgery. (Mohs treated cancer successfully in more sites than just the skin.) One could “follow the tumor” (i.e., custom tailor the excision to each individual patient). If tumors could be subdivided into manageable subunits, locally early, intermediate, and even some locally advanced laryngeal cancers might be candidates.

Of course, transoral cordectomy provided outstanding results long before the laser was added. Suspension and the microscope were the keys, not a laser. What the laser added was questionable—costs for new equipment, time to set up, regulations in the operating room, thermal injury hazards, maintenance issues, anesthesia issues, more suction, filters, retraining requirements, and new credentialing. And what the laser gave up was considerable—the tactile feedback of cold steel microinstruments, the ability to cut around corners, the plume-free operating site, the char-free pathology specimen, operating room space, an unencumbered microscope, and the precision of a cut path versus a vaporization path.

But in the 1980s and 1990s, a sustained experience of endoscopic laser surgery for glottic cancers larger than T1a was growing in Germany. This raised additional questions among traditionalists. They had concerns about exposure, hemostasis, reconstruction, margins, and wound healing. The greatest concern, however, was tumor transection. Steiner cut right through laryngeal cancer—in situ—through a laryngoscope. The claimed advantage was visualization and confirmation of tumor depth. How did the skeptics respond? First, they were asked to compromise access and work through smoke with an endoscope, with no convincing evidence this was meaningful. Then they were asked to give up orientation and violate the principle of en bloc resection—with no laboratory evidence this was safe.

Other concerns fueled the discussion. After a laser supraglottic resection, there was no reconstruction. Open supraglottic laryngectomy always led to aspiration if one failed to repair the gap between the glottic unit and the tongue base. After laser SCPL, there was no CHP. Yet this was essential in open SCPL. There were so many additional issues a laser did not address (e.g., bleeders over 2 mm, ossified cartilage, and neck nodes).

Furthermore, the obvious problems of access were troubling. Big tongues, small mandibles, capped teeth, mild trismus, and other challenges all lay in waiting, even for the most resourceful of operators. Very early midcordal T1a carcinomas may have been fine. But early cancers would require greater exposure, intermediates more, and so on. Some would be too big to extract through an endoscope. A growing plethora of “laser laryngoscopes” raised suspicion that the problem of access remained unsolved.

Another challenge would be quality control from the pathology department. In cancer operations, negative margins are compulsory. If laser specimens were vaporized, the pathologist would have no margins to read. If they were excised with a laser, margins would at best be charred. If they were excised in several pieces, positive margins would be meaningless!

In North American practices, these considerations delayed TLM. This occurred despite much of the pioneering work originating in North America—the entire organ serial section studies from New Haven, Philadelphia, and Toronto; the development of the CO ₂ laser itself at American Optical Corporation by Strong and associates in 1965; and the pioneering clinical laryngology of Strong; Jako, Vaughan, Davis, and Ossoff and their coworkers; and Shapshay. But the German centers were leaders in the collaborative development of all the ancillary laryngologic instrumentation needed to capitalize on the technique. They pushed their experience well beyond the concerns recited earlier, tracked their results, and continue to report on their experience.

In 1996, the authors of this chapter began to study this body of work more closely, and subsequently we took numerous steps to incorporate TLM into our practices. This effort provided new perspectives on laryngeal cancer management and the initial selection of therapy. Now we seek to share what we have learned.

Theoretic Basis of Transoral Laser Microsurgery

TLM does violate a time-honored dictum of surgical oncology—en bloc resection. A typical glottic or supraglottic cancer (above T1) is likely to be extracted in three to six separate pieces.

En bloc has always been a prudent tactic to avoid unseen physical dispersion of viable malignant cells in a wound. When a scalpel penetrates cancer, the cells exposed will be alive. Viable cancer cells may adhere to the blade. Nothing prevents the surgeon from inadvertently transferring unseen cancer to an adjacent site in the wound. If unseen cell transplantation does occur during open surgery, and then we close the wound, how could tumor not recur? In open traditional surgery, this is why we isolate cancer in an unbroken package of normal surrounding tissue—to prevent contact between cancer and a scalpel or a scissor. This way, maybe we can avoid transplanting living malignant cells from the cancer back into the patient.

Rethinking this chain of events in laser microresections raises a new question. What would be the apparatus of physical transplantation? Cancer cells do not adhere to a beam of light. There is no physical carrier to transplant the tumor. Then again, grasping forceps and the suction cautery tips are used in TLM. They could do it. But assuming no tearing of the specimen, how would exposed cancer cells be viable? Cells revealed by laser energy are thermocoagulated, not viable. Finally, in the TLM paradigm, we do not close the wound. An unseen cancer cell falls on a thin layer of coagulum, not a healthy tissue surface. This layer is gradually sloughed, not incubated.

These are theoretic reasons we postulate that laser surgery permits local cancer ablation without en bloc resection. Are there any laboratory or clinical data? Werner and colleagues showed (for CO ₂ laser incisions) that the lymphatic vessels of the wound margin are sealed immediately, and lymphatic vessels remain sealed for about 10 days after laser surgery. And we also have 20 years of European clinical data. Steiner and colleagues have been performing TLM since the early 1980s. He and his colleagues have observed a low local recurrence rate (2% to 10%), a high survival rate, and a low rate of complications. They have not seen an increase in late neck or distant metastases during follow-up of more than 10 years. The incidence of cure by TLM is the same as the best results reported for open conservation surgery. Put another way, open surgery follows the principle of block resection but produces no more local cures than TLM. TLM allows laser tumor subdivision, but local failure occurs with the same low incidence as in traditional open conservation surgery.

If tumor transection can be safely accomplished (it is not automatic, care is still important), we have an attractive new technique to determine the depth of cancer invasion before we commit to the plane of excision. If we misjudge and cleave too close to the tumor, this is just another form of tumor transection. We can extend the excision, incrementally. All we have lost is some time.

If tumors can be divided in situ, the tumor itself ceases to be a factor in obstructing our vision. Complete removal always requires that we expose the entire mucosal margin of the tumor. Now we can achieve that goal in a mosaic of views, unrestricted by the bulk of the disease.

If tumors can be extracted in pieces, the internal diameter of the laryngoscope does not set the limit on how large a tumor we can resect. The limit becomes the exposure for each step and our disciplined attention to specimen orientation. Mohs transected cancers in situ successfully, and his attention to orientation was uncompromising.

Later in this chapter, we summarize our TLM results, as well as those of others. We have documented a low incidence of failure at the primary site and also reported the ultimate causes of death. Our conclusion is that ultraradical treatment of the primary is not justifiable in a disease for which the main causes of death are advanced neck recurrences, distant metastases, second primaries, and serious general diseases. In modern times, quality of life is increasingly salient. In related diseases like hypopharyngeal cancer (TLM treats pyriform cancer, too ), 5-year survival rates have stood between 15% and 30% for decades. Aggressive combined therapy (chemotherapy, radiotherapy, and radical surgery) have not improved the poor prognosis. Again, if we can effect local control with conservation laser surgery, the argument in favor of radical ablation clearly declines.

Transoral Laser Microsurgery Compared With Open Conservation Surgery

Open operations approach intralaryngeal carcinoma from its “blind side.” The surgeon cannot see the primary cancer until he or she has opened the neck, divided the fascia, separated the strap muscles, opened the framework, and penetrated the lumen at a critical point, determined by the local anatomy. Once exposed, field margins are oozy, not laser cut. Structures within the field relocate with the surgery, instead of maintaining a fixed position. The tumor margins are diminutive, not magnified, and the headlamp is illuminated, not microscope super-illuminated. For safety and reproducibility, open operations closely replicate a named excision block, chosen without the benefit of intraoperative depth information. For example, supraglottic laryngectomy removes the superstructures above the cords, which produces a predictable wound, requires a characteristic reconstruction, and can be repeated for numerous supraglottic cancer patients, despite the fact each has unique anatomy, distinctive preoperative findings, and slightly different tumor characteristics. Because the neck will be opened, the timing of a node dissection is determined. The neck dissection is continuous with the primary wound, so steps must be taken to prevent a fistula. Because the framework is elevated to the tongue base and both swell, airway safety demands a temporary tracheotomy. Supraglottic laryngectomy supports the principle of en bloc resection, but this was necessitated by the scalpel, not the cancer. It assists teaching, but for gross anatomy, not for the microanatomy and micropathology. Open supraglottic laryngectomy provides the access needed for reconstruction, but the open surgery necessitated the reconstruction.

By approaching laryngeal carcinoma through the mouth, TLM requires no disassembly for access. The laryngeal framework continues to support the airway. A tracheotomy is usually superfluous in a supraglottic TLM. The strap muscles retain their swallowing contribution. Through the endoscope, the operator confronts the authentic primary right from the beginning of the resection, with no disassembly of the patient just to reach the cancer. The laryngoscope stabilizes the field. The magnification and brilliant illumination unveil important subtleties (e.g., dysplasia at a margin). With no disturbance of the neck, and no connection of a neck wound with a laryngeal wound, pharyngocutaneous fistulae disappear from the list of potential complications.

During TLM, diagnosis continues. Wherever the local tumor extends, the microscope and the laser try to follow. Magnified tissue appearances acquire new significance. Some tumors change the vascular patterns in the mucosa. Deeper in, invasive cancer tends to appear pale and dysmorphic. Tissues give up subtle information about their consistency as they are retracted. Cancer is stiff or soft (soft can progress to friability and bleeding). Beyond the tumor, the expected microarchitecture is striated muscle, fat, seromucinous glands, fibrous perichondrium, (ossified) cartilage, or bone. Fat looks yellow and lobulated; mucous glands are pale and lobulated but more noticeably vascular. Muscle is striated. Fibrous tissue is white and dry. Ossified cartilage and bone carbonize to a dominoes-like appearance. The undersurface of the strap muscles is loose and areolar.

TLM is a natural ally of combined treatment. Once the tumor is out, the locoregional microvasculature is still undisturbed—the best milieu for postoperative radiotherapy. And complete three-dimensional resection under the microscope has minimized the chances of a positive margin.

During the weeks after TLM, the endolaryngeal wound heals by secondary intention (in many ways similar to a tonsil bed). The framework resists stenosis because it remains intact. The thermal damage from laser resection is superficial (after electrocautery, it is deeper). No local flaps are mobilized or transposed, so there is no chance to bury residual tumor. “Second-look” endoscopies become a meaningful way to revisit the primary site.

Months later, persistent granulation may signal the need for endoscopic removal to improve voice. Follow-up laryngoscopy also allows the removal of small, ossified cartilage sequestra, which sometimes develop after laser resection has been carried down to the framework. Reepithelialization seems to forecast recovery but does not completely eliminate all risk of recurrence. Not even a negative second look excludes later recurrence. An overhanging anterior glottic scar may hide an unsuspected nubbin of residual tumor—still a salvageable circumstance, by simple laser resection, if discovered in time by this tactic. Before recommending TLM, discuss the willingness of the patient to return for a second look.

Instrumentation and Techniques of Transoral Laser Microsurgery

Techniques

To enhance endoscopic exposure of the anterior commissure, one can laser-transect the ventricular bands (i.e., the inferior free margin of the false cord or upper lip of the ventricle) from their anterior anchorage on the framework of the larynx. But this diminishes the contribution undisturbed false cord tissues might have made to voice (exposure of the anterior commissure for lasering presupposes that the anterior glottic contribution to voice will be lost).

Do not rely completely on the pathologist. Study the mucosal margin around the tumor yourself. The operator enjoys the advantage over the pathologist when it comes to dodging a falsely negative margin reading. The pathologist will only see some of the margin—a rolled edge, with its telltale vascular network empty and collapsed. The surgeon gets to view the living margin under brilliant illumination, extended by traction, and further described by its vascular patterning.

Once beneath the mucosa, follow the cancer in an orderly way. Use your knowledge of cross-sectional anatomy. Use the telescopes to inspect beyond the tumor. Use the power of laser surgery to resect one piece at a time and maintain constant orientation. Replace finger palpation with instrument palpation. Pull the tumor into the field with grasping forceps. Finish an area before changing the tension and exposure in favor of another.

For laryngeal cancers that we choose to remove in sections, the plan of TLM is to complete each subresection a block (or view) at a time ( Fig. 107.2 ). Use transection at the edge of the field to find the healthy tissue plane and deliver all the cancer that will be taken in that established view. Tumor transection defines the plane of separation from the rest of the cancer. Consider marking it with ink. This surface will be the plane we need to place within the next view we “capture,” to maintain a continuous resection. Like a Rubik's cube, as each new tumor subcomponent is delivered, an adjacent component becomes more accessible.

As each subunit is resected, three obligations are paramount:

• 1

  Maintain continuous orientation to the cancer. Recognize what has been completed and what next to expose. Know what remains to be done.

• 2

  Orient the resected specimen for the pathologist. The deep margin is the margin of interest, not the margin released from the rest of the tumor, which is known to be cancerous. It usually remains unmarked or bears the specific color we use to designate tumor transection surfaces.

• 3

  Ink the deep surface margins and the peripheral margins, which are expected to be negative, with the previously agreed on study color (usually blue).

Any time TLM is applied to locally intermediate or advanced cancer, some patients will present with significant disease in the subglottic larynx. This can be a challenging location for exposure. Among the most helpful ploys are a small endotracheal tube, proper choice of the endoscopes, top-to-bottom sequencing of the resection, and special positioning of the larynx. Tip the larynx up by elevating the thyroid cartilage with the laryngoscope blade and depress the cricoid with cross-table taping. Most patients with subglottic cancer have glottic cancer. Excise the glottic component first and exposure is automatically improved for the subglottic disease. When cancer descends to the inferior margin of the thyroid cartilage, include the cartilage margin itself in the resection. It is possible to encounter (and recognize) the Delphian node when laser resections extend forward through the lower margin of the thyroid cartilage. Resection with the cricothyroid soft tissues provides an opportune method to identify an important mode of extralaryngeal nodal spread, a finding that usually calls for further treatment of the nodes in the neck. Laser resection and histopathologic study of the Delphian node should probably be a routine part of any significant subglottic resection.

TLM is not just a simple combination of already familiar techniques. It forces us to reconsider the detailed anatomy of the larynx—to learn it “inside out.” Otolaryngologists introducing TLM into their practice should watch someone do it. Take a course. Be prepared to train an assistant and a scrub nurse too. If facilities permit, fresh frozen cadaver dissection has merit. Some of the goals would be to distinguish the greater horn of the hyoid versus the upper edge and cornu of thyroid cartilage, the preepiglottic fat versus the glands around the ventricle, the distribution of the superior laryngeal artery and its main branches, the form and attachments of the conus elasticus, and other parts of the neck.

If you biopsy a cancer at a separate sitting, use this opportunity to evaluate your preparedness and equipment for TLM. Determine whether your exposure will be adequate. When it comes to making the transition from study and observation to practice and application, start with small cancers and edentulous patients, the easiest to expose. Then work your way up.

Evolution of Potassium Titanyl Phosphate Laser Microsurgery

A major benefit of TLM resection techniques is that they result in maximal preservation of noncancerous tissues. This allows for an increased chance of intact function following surgery and provides tissue for reconstruction if needed. Tissue preservation is of utmost importance in the larynx where a millimeter of tissue can make the difference between function and dysfunction.

In the early 1980s, R. Rox Anderson conceived of selective photothermolysis for the treatment of dermal vascular lesions. As a result, two photoangiolytic lasers were developed: the 585-nm pulsed-dye laser (PDL) and the 532-nm pulsed-potassium-titanyl-phosphate (KTP) laser. These wavelengths precisely target the absorbance peaks of oxyhemoglobin (around 571 and 541 nm). This allows laser energy to be applied in a pulsed mode within blood vessels and have relative sparing of the adjacent extravascular soft tissue if so desired. Alternatively, if the objective is to heat extravascular malignant soft tissue, the laser energy could be administered with greater power and/or a continuous wave mode. Over the course of time, the solid-state pulsed KTP laser has been found to be a more versatile, precise, reliable, and effective technology.

The transition of this laser technology from dermal vascular lesions to the larynx was based on the understanding of tumor growth characteristics. In 1966, Jako and Kleinsasser first described the concept of aberrant neovascularity. This was followed by a description of intralesional tumor angiogenesis by Folkman in 1971. Tumor angiogenesis is particularly crucial for growth on the relatively avascular vocal folds. Knowing the importance of tissue preservation to overall laryngeal function, the use of an angiolytic laser to ablate tumors and provide sparing of normal adjacent tissue was a logical next step.

The concept of photoangiolytic lasers for the treatment of laryngeal pathology was first introduced in the late 1990s. The selectivity of these lasers provides maximum preservation of the layered microstructure of the vocal fold and leads to improved vocal and functional outcomes. Photoangiolysis has been shown to be effective in treating a number of laryngeal lesions, including papillomatosis, dysplasia, microvascular angiomata, and early glottic cancer. For the treatment of premalignant and malignant epithelium, these lasers can be used in different ways. First, the unique capabilities of photoangiolysis allow for ablation of underlying vasculature without altering the structure of epithelium. This action effectively decouples premalignant epithelium from the superficial lamina propria (SLP) and improves the precision of microflap dissection of dysplasia. Conversely, the laser can involute disease by ablating both the intralesional and sublesional microcirculation of the dysplastic lesion. Finally, angiolytic lasers can be used in a similar fashion to the CO ₂ laser and perform a tumor resection.

In 2008, Zeitels et al. first described the use of angiolytic lasers for the treatment of early glottic cancer. The initial pilot study consisted of 22 patients with early glottic cancer (13 T1, 9 T2) treated with an angiolytic laser. The mean follow-up was 27 months, at which time no patient had a recurrence. In this initial series, objective measures of vocal function revealed significant postoperative improvements despite the fact that half of the patients had bilateral disease. The Massachusetts General Hospital group has since demonstrated further success both with a larger cohort and with longer follow-up. They have also reported excellent voice results with objective vocal outcome measures on over 90 patients. Finally, they have demonstrated promising results using microlaryngoscopic KTP laser salvage after failed radiotherapy.

The versatility and selectivity of the KTP laser makes it an attractive option for the management of head and neck pathology. As described, the KTP laser is particularly useful for early glottic cancer. However, it can be applied to more locally advanced head and neck tumors. The laser can be used either in continuous or pulsed modes. Pulsing the laser makes the energy delivery time less than the thermal relaxation time of the tissue. This allows tissue to cool between pulses. As a result, extravascular soft tissue thermal damage is decreased when compared to continuous mode. This is ideal for ablation on the vocal folds where maximal preservation of the layered microstructure is paramount. Also in pulsed mode, the laser does not penetrate deeply and has diminished absorption in the adjacent normal tissue. The differential absorption between cancerous and normal tissue provides excellent visualization of the tumor margin, which can be confirmed by frozen section if needed. Continuous mode is also excellent for more traditional resection techniques where the fiber can be used as a tangentially directed light scalpel similar to a CO ₂ laser. However, it is advisable to use an external cooling system during continuous mode due to the increased heat generated.

We use the 532-nm pulsed KTP laser (Aura XP, Laserscope, San Jose, CA) in our institution ( Fig. 107.3 ). For most lesions involving the vocal fold, a 0.3-mm fiber is used and the laser is set to between 30 and 35 W, l5-ms pulse width, and 2-Hz repetition rate. For supraglottic and subglottic lesions, the energy output can be increased as needed, allowing for a more expedited ablation. However, the higher the energy setting, the higher the heat transmitted to adjacent structures. The small amount of increased collateral damage in these areas is better tolerated compared to the specialized vocal folds. When used in continuous mode, we usually set the laser between 2 and 10 W in an effort to minimize thermal damage.

Many laryngeal pathologies, such as papilloma, leukoplakia, and cancer, are recurrent in nature. Adequate management would typically require multiple trips to the operating room, subjecting patients to many general anesthetics and the inherent risks of surgery. Angiolytic lasers helped to facilitate the transition of the postoperative management of these disorders to the office. Unlike the CO ₂ laser, angiolytic lasers deliver energy through thin glass fibers. These small, flexible fibers are perfectly suited to use through the channel of the flexible laryngoscope. In our practice, all patients presenting with one of these disorders are first taken to the operating room to precisely treat the areas of concern. Patients are then transitioned to the office setting as tolerated for follow-up and management of small recurrences. Given that office-based treatment tends to be less precise than the operating room, we recommend that surgeons just starting to treat these disorders begin with treatment in the operating room and gradually transition to the office setting.