Lasers find many niches in medical diagnosis and care

Lasers find many niches in medical diagnosis and care

Kathy Kincade Contributing Editor

Welcome to Medicalwatch, a new monthly column that will provide an overview of laser-based medical technologies, the clinical areas in which they are used, and the im pact they are having on the delivery of modern health care. It will also serve as a forum for the discussion of emerging and evolving technologies and markets (see table) and the ups and downs of the various players in these markets. Ultimately, it should give readers a better understanding of how medical-laser devices are designed, marketed, and used.

Currently, the strongest markets for surgical lasers are in dermatology/plastic surgery, ophthalmology, and cardiology. In fact, despite the slowdown in sales of carbon dioxide (CO2) laser systems for skin resurfacing, the surgical-laser market is expected to grow 19% in 1998. This increase is due in large part to continued consumer interest in cosmetic applications, particularly skin resurfacing and hair removal, as well as steady growth in the number of vision-correction procedures--primarily photorefractive keratectomy (PRK) and laser-assisted in situ keratomileusis (LASIK)--being performed and the expanding use of lasers for transmyocardial revascularization (TMR) and related cardiovascular applications.

Newer laser technologies are also having an impact on the medical-laser market. The erbium-doped YAG (Er:YAG) laser emitting at 2.94 µm is gaining favor for a variety of applications in dermatology, ophthalmology, and dentistry. In addition, ongoing refinement of diode-laser technology is prompting broader use of these devices for applications ranging from hair and leg-vein removal to tissue welding and optical diagnostics. In fact, this technology is helping to accelerate the development of laser-based diagnostic products for such applications as optical biopsies and tumor detection, and sales of diagnostic-laser devices are expected to reach $150 million in 1998.

Cosmetic applications

Of the many cosmetic-laser procedures now available, skin resurfacing has been credited with almost single-handedly resurrecting the medical-laser market in the 1990s. And rightly so. However, the market for CO2 resurfacing lasers is all but saturated, and in the past two years the erbium laser has gained favor as a "kinder, gentler" resurfacing tool, with the added benefit of being able to treat the neck and hands.

Nonablative approaches (primarily holmium-laser-based) are also being developed, and "skin rejuvenation"--in which the laser does not remove tissue, but initiates cellular changes and some sort of healing response--could become the next generation of laser-based wrinkle removal.

More recently, hair removal has become the darling of the cosmetic-laser industry. More than a dozen companies are now selling laser-based hair-removal systems (based on Nd:YAG, ruby, alexandrite, and diode systems), all vying for a piece of this billion-dollar-a-year market. The large number of vendors, however, has created confusion among potential customers, many of whom are having a hard time distinguishing one product and wavelength from another. In addition, lasers have yet to attain the Holy Grail of permanent removal and are competing not just with one another but with more-established hair-removal techniques, such as electrolysis.

Leg-vein removal is another potentially lucrative cosmetic application. While dye lasers have been in this market for some time, they have had a hard time competing with more-established treatments, such as sclerotherapy. But diode lasers offer a more compact and cost-effective alternative, and at least three companies--Palomar, Diomed, and ESC--have developed diode-laser systems that can be used for both hair and leg-vein removal.

Cardiologists await TMR

Transmyocardial revascularization has become the bright spot for lasers in the cardiovascular market. In TMR, a laser is used to drill holes in the heart to increase the flow of blood to oxygen-starved tissue and relieve the pain and other symptoms experienced by patients suffering from angina. The procedure is intended to be an alternative for patients who are not candidates for bypass surgery or angioplasty--a market estimated to be worth around $1 billion.

PLC Systems (Franklin, MA) pioneered TMR, and the company`s high-power CO2 laser has been used on hundreds of patients. Although an FDA panel rejected PLC`s first premarket approval application in July 1997, saying the clinical data was "inadequate and troubling," the company finally received the first FDA clearance of a laser for this aplication in August of this year.

But at least eight other companies are developing competing laser systems, including Eclipse Surgical Technologies, Cardiogenesis, US Surgical, Acculase, Cardiodyne, Circulase, Cormedica, and Laser Industries. Of these, Eclipse Surgical and CardioGenesis are furthest along in the FDA cycle; both have holmium-laser systems and use a less-invasive approach called PMR (percutaneous myocardial revascularization), and both are anticipating FDA clearance sometime in 1999. The other companies are in various stages of product development and clinical trials with excimer- and holmium-laser-based systems.

LASIK challenges PRK

Although the market for laser vision correction continues to increase, sales of ophthalmic-laser systems are showing a negative growth rate (-6%) for the first time since 1985. Sales of ophthalmic lasers rose only 9% in 1997, to $360 million, compared to a 25% increase between 1995 and 1996. And this downward trend is expected to continue in 1998, with revenues falling to $340 million.

It is interesting to note that although sales of refractive surgery lasers are down, procedures are on the rise. There is currently a shift, however, away from PRK and toward LASIK, even though the FDA has yet to grant clearance to any commercially available laser for LASIK.

Despite the trend away from PRK, several second-generation PRK lasers are poised to enter this market in late 1998 or early 1999--from Autonomous Technologies, LaserSight, and Chiron. These excimer-laser systems will likely be lower-priced and will feature advanced tracking systems. In addition, Sunrise Technologies is still pursuing its holmium-laser refractive technique and is currently in Phase III trials for treating hyperopia (farsightedness). Ultrafast lasers are also being studied for refractive-surgery applications.

Diode lasers in PDT and diagnostics

Photodynamic therapy (PDT) is beginning to emerge as a true alternative for the treatment of cancer and other illnesses. Worldwide sales of lasers for PDT are growing at a steady 10% annually and are expected to reach $60 million in 1998. Laser systems include dye, Nd:YAG, and diode; laser companies actively involved in this market include Coherent, Laserscope, Diomed, Physical Sciences, and Photogen.

But PDT is more than just a cancer treatment; it is also undergoing study for the treatment of age-related macular degeneration, psoriasis and other skin diseases, blocked arteries, and hair removal. The expansion of clinical applications for PDT is due in part to the growing number of photosensitive drugs undergoing clinical evaluation and the increasing viability of diode-laser systems for PDT.

Diode lasers are also contributing to the expanding diagnostic market, with applications ranging from fluorescence and Raman spectroscopy to fluorescence lifetime imaging, photon migration, and multiphoton excitation. Much of the current R&D work is focused on early detection of cancer and other diseases, optical biopsies, and monitoring of blood glucose and gases, and the market potential for compact laser systems and fiberoptic probes is especially strong in this arena.

Although the commercial development of optical diagnostics has been slow, several companies are currently in clinical trials. Five of them are described here.

Xillix (Richmond, BC, Canada) has a HeCd-laser system that uses fluorescence to endoscopically detect precancerous conditions in the lung, GI tract, and ear, nose, and throat. This system has FDA clearance for use in the lung; its GI-tract application is pending.

SpectRx (Atlanta, GA) has three optical diagnostic products in various stages of development, including a laser-based diabetes screening system that works by measuring fluorescence in the lens of the eye. The company also has an exclusive license to 22 fluorescence-lifetime spectroscopy patents and has spun off another

company, FluorRx, to develop noninvasive, point-of-care diagnostic workstations based on this technology.

Mediscience (Cherry Hill, NJ) is the commercialization arm for the optical imaging and diagnostic technology being developed by Robert Alfano and colleagues at the City College of New York. The firm is developing a variety of noninvasive medical instruments that use native tissue fluorescence to detect cancer and precancerous conditions.

SpectraScience (Minneapolis, MN) is in clinical trials with its optical biopsy system for the early detection of esophageal cancer and has completed a multiple-center clinical trial for the early detection of colorectal cancer.

Laser Diagnostic Technologies (San Diego, CA) is developing a field-portable digital ophthalmoscope for the US Army. The diode-laser device, which will transmit real-time images of soldiers` eyes from the battlefield to a physician behind lines, could become commercially available in about two years.  o

KATHY KINCADE is editor of PennWell`s Medical Laser Report, a monthly newsletter covering business, clinical, and technology trends in the medical-laser industry. Comments and suggestions for future columns are welcome at tel.: (510) 923-1123 or e-mail: [email protected].

Clarification

The article "Raman spectroscopy enhances in vivo diagnosis" (Laser Focus World, July 1998, p. 83) contained some oversights regarding the development of near-infrared Raman spectroscopy for tissue analysis. Dr. Robert Alfano and colleagues from City College of New York (CCNY; New York, NY) first reported their work in this field in August 1990, several months before Dr. Michael Feld and his colleagues reported their research in December 1990. Alfano and his group at the Institute for Ultrafast Spectroscopy and Lasers continue to investigate various optical-fiber probes for remote Raman scattering measurements in tissues, keeping the diameter of the probes below 3 mm in order to fit them into endoscopes for in vivo use. They reported on this work at the February 1997 SPIE BiOS meeting in San Jose, CA.

CCNY holds two US patents (#5,261,410 and #5,293,872) regarding the use of Raman spectroscopy for cancer and calcified atherosclerotic tissue detection and has a patent pending on filtered fiber technology similar to that developed by Visionex (Warner Robins, GA). In fact, Visionex references the two CCNY patents in its literature, noting that its fiber products cannot be used for making certain tissue classifications related to cancer or atherosclerosis in accordance with the claims of patents #5,261,410 and #5,293,872.

We regret any inconvenience these oversights may have caused.--Ed.