Photodynamic therapy's potential applications overlooked

West Palm Beach, Fla. - All the attention paid to medical lasers’ aesthetic indications has overshadowed the fact that lasers’ utility for treating medical conditions continues to grow, an expert says.

“Lasers usually attract a lot of attention for cosmetic indications. But there are many medical uses today, and many more that we haven’t yet explored,” says Jill Waibel, M.D., a dermatologist in private practice at Palm Beach Esthetic Dermatology & Laser Center, West Palm Beach, Fla., and a volunteer faculty member with the University of Miami department of dermatology.

Skin cancer

Photodynamic therapy (PDT) is probably the most important underused laser technology in terms of U.S. medical applications, Dr. Waibel says.

“In Europe, not only are physicians starting to use PDT for skin cancer, but they’re also starting to use it for ovarian cancer and other cancers. We know that PDT prevents skin cancer and treats precancers of the skin,” yet the United States healthcare system spends billions of dollars annually to freeze actinic keratoses (AKs) or to excise skin cancers only after they’ve occurred, she says.

However, PDT has several barriers - including the amount of time patients must spend in the office, post-treatment photosensitivity and reimbursement issues - that prevent widespread use at present, Dr. Waibel says.

Also in the area of skin cancer, Dr. Waibel says her colleagues are doing preliminary research with laser-assisted imaging systems that would allow a dermatologist to view skin cancer down to the microscopic level while it’s still on the body.

“This technology could reduce costs and improve efficacy,” she says. “And if we could use a microscope with a laser attached to look at a patient’s skin, we could possibly even treat the skin cancer at the same time. Now that’s exciting.”

Additional applications for PDT include treating actinic cheilitis, basal cell carcinoma nevus syndrome and disseminated porokeratosis, Dr. Waibel says, adding that she’s also achieved very good results with PDT in treating acne keloidalis nuchae, pseudofolliculitis barbae and hidradenitis suppurativa.

Additionally, European researchers have begun exploring the possibility of spraying on the photosensitizing agent aminolevulinic acid (ALA). Researchers were to give a presentation at the American Society for Laser Medicine and Surgery conference this year about delivering ALA after ablative fractional laser treatments to enhance its penetration.

Acne vulgaris

Conversely, with acne vulgaris, “PDT is an option, but it has fallen short. That’s something we need to work on,” Dr. Waibel says. New photosensitizers being studied in this regard include indole-3-acetic acid and methyl aminolevulinate, she says.

Furthermore, Dr. Waibel reports that work is being done to decrease pain while using the 1450 nanometer diode laser for acne.

“The 1450 diode laser has been shown to be effective for acne,” she says. “However, teenage patients could not tolerate the pain.”

Using laser treatments for acne assumes increased importance in light of the difficulties created by the Food and Drug Administration’s (FDA) isotretinoin risk-management program, and the fact that teenagers’ rates of compliance with topical and pharmaceutical treatments are notoriously low, she adds.

“If a patient could come in once every one to three months for a laser treatment instead of having to take a pill or apply a cream two or three times daily, that would be a much more cost-effective and compliance-maximizing treatment for acne,” Dr. Waibel says.

Other uses

Another promising possibility that could yield fruit in the future is nanosuturing - utilizing light (not heat) generated by medical lasers in conjunction with light-activated dyes such as Rose Bengal to close surgical wounds without stitches. In this area, Dr. Waibel says researchers at Massachusetts General Hospital’s Wellman Center for Photomedicine are leading the way.

For burn patients experiencing functional and cosmetic problems due to scarring, Dr. Waibel says she recently completed a study using the Fraxel (Solta Medical) device. In the study, she says, “Patients experienced great results on all counts, including functionality, cosmetic concerns and self-esteem issues.” Perhaps within the next five years this laser device may be used in the medical arena as a drug-delivery system, she adds.

Regarding the treatment of port wine stains with vascular lasers, she says recent research reinforces that patients fare best if physicians begin treating these problems early (Chapas AM, Eckhorst K, Geronemus RG. Lasers Surg Med. 2007 Aug;39(7):563-568). “One can treat an infant with port wine stain as early as two weeks of age and every two weeks thereafter,” Dr. Waibel says.

One relatively new treatment for port wine stains involves the alexandrite laser, which is usually used for pigmentary problems, she says.

“Typically, the laser of choice for port wine stains is the 595 nm pulsed dye laser. But one problem with this technology is that it only penetrates a few hundred microns,” Dr. Waibel says. “As a result, patients (particularly adults) often experience incomplete clearing because the vessels lie deeper, and the port wine stain is not completely eliminated or recurs.”

To solve this problem, “We had tried the 1064 nm Nd:YAG laser because it penetrates very deeply, but it wasn’t specific enough.”

Conversely, she says the 755 nm alexandrite laser not only targets melanin effectively, “But it also has a very good vascular absorption curve. For port wine stains that had failed treatment with the PDL, a study has shown the alexandrite can produce excellent results (Izikson L, Anderson RR. J Cosmet Laser Ther. 2008 Nov 13:1-4).”

Furthermore, she reminds dermatologists to watch for dangerous syndromes that can be associated with port wine stains. Examples include Sturge-Weber syndrome (encephalotrigeminal angiomatosis), which is marked by tram track calcifications in the brain cortex. Klippel-Trenaunay-Weber syndrome, Cobb syndrome and Proteus syndrome represent a few other examples.

At the same time, Dr. Waibel says Harvard-based investigators Rox Anderson, M.D., and Mathew Avram, M.D., are exploring the medical consequences of laser-assisted fat lipolysis. Apart from the cosmetic impact of these treatments, she says their research could help answer questions including whether fat lipolysis has the potential to help patients with diabetes.

One new device for treating fat and cellulite that could enter the U.S. market is a fat-cooling device (Zeltiq), she says. Additionally, “Elemé has introduced the SmoothShapes ultrasound-based device for cellulite. And Medicis is bringing its Liposonix device onboard.”

Also, Dr. Waibel says a means of lipolysis (developed by Canadian researcher Andrei Kabashin, Ph.D.) that involves injecting a liquid containing nanoparticle-sized bubbles into fat and then heating the liquid could prove an effective tool for lipolysis. Ultimately, physicians may be able to use such products in a more medical way, not just for aesthetically decreasing fat, she says.

Regarding hair removal, Dr. Waibel says dermatologists should watch for several diseases that can produce increased body hair. For example, “When people walk in the door with significant increased hair, it can stem from medication, a cancer or other issues,” she says. In particular, some patients with lung or other cancers can develop significant amounts of hair abruptly.

Likewise, she says many patients with polycystic ovarian syndrome present with increased hair growth.

“I have seen a lot of late-onset congenital adrenal hyperplasia associated with hirsutism. One of my concerns is that it’s fairly simple to purchase and operate a hair removal laser.”

And while many states allow nonphysicians to operate such lasers, “Patients certainly need a consultation with a physician who can appropriately evaluate the reason for the increased hair,” Dr. Waibel says.

Disclosures: Dr. Waibel has been a lecturer for Reliant (now Solta Medical), Candela and Lumenis. She also has received a research grant from Reliant but owns no stock in the company or in Solta Medical.