Using Light to Ward Off Oral Cancer
Having cancer inside your mouth is a disturbing and often stressful reality. This condition is generally referred to as oral cancer, and it involves the uncontrollable growth of malignant cells that damage various structures within the mouth such as the lips, tongue, cheeks, and floor of the mouth. Such growths can be life-threatening if not diagnosed and treated early. The optimal strategy, of course, would be to find ways to prevent such cancer from developing in the first place.
Oral leukoplakia is the most common health problem affecting the mouth that can eventually develop into cancer. This condition shows up as a thickened white patch on the insides of your cheeks, on your gums, on the bottom of your mouth, or even on your tongue. The patch will not rub off. The usual treatment is to remove it surgically using a scalpel or laser, or by using an extremely cold probe that freezes and destroys cancer cells (cryotherapy).
By treating oral leukoplakia at its earliest stage, the incidence of oral cancer can be greatly reduced. The problem with the conventional treatment methods, however, is that they can cause pain and discomfort, as well as damage to tissues within the mouth. Fortunately, a less invasive alternative is proving to be effective for this potentially malignant disorder: photodynamic therapy, or PDT.
PDT is a light-based therapy has been successfully used to treat oral leukoplakia and offers certain advantages over conventional treatments:
- PDT is noninvasive and well-tolerated.
- PDT will not damage the normal tissues and moreover produces good cosmetic results.
- PDT can be used when surgery is contraindicated, such as for patients with pacemakers or bleeding disorders.
- PDT can be used repeatedly (without side effects) if any additional patches of leukoplakia are found.
What the Most Recent Research Shows
At this time, PDT has been studied in only a small number of patients with this oral health problem. The most recent study comes out of Tamil Nadu Government Dental College and Hospital, in Chennai, India. Five patients were treated with PDT for six to eight sessions and then observed for one year.
The Chennai study used a cream containing aminolevulinic acid (ALA) as the photosensitizing agent. This compound stimulates the production of a natural photosensitizer (Pp-IX) that then accumulates in the patches of leukoplakia. Upon exposure to light of a specific wavelength, and in the presence of oxygen, this treatment results in the destruction of the patches of abnormal cells.
The findings were as follows. The Pp-IX reached its maximum concentration in the leukoplakia patches within three hours of having the ALA ointment applied to the lesion. The level of Pp-IX began to decline very quickly after four hours. Two days after the treatment, the levels returned to normal. Because of this, patients did not need to take any precautions concerning light and sun exposure after two days.
One month after the treatment, two of the five patients had shown a complete elimination of the problem, while two others had partial responses, i.e., not all leukoplakia patch was gone. The less responsive cases had thicker patches that made penetration of the light and photosensitizer difficult. The researchers suggested that this problem could be overcome with successive PDT treatments.
In summary, PDT was most effective against leukoplakia patches that are thinner and smaller (no larger than one centimeter), pinkish (mixed red and white lesions), and with some amount of dysplasia (a type of abnormal cellss detectable with a microscope). Light treatment appears to be optimal when given between three and four hours after the administering the ALA cream. Notably, there was no recurrence in any of the four responders, and none of the patients experienced any side effects. The fifth patient failed to respond and was treated with conventional methods.
Concluding Thoughts, Preventing Oral Cancer
The Chennai scientists concluded that ALA-PDT appears to be a promising alternative way to treat oral leukoplakia. These response rates are similar to those of other studies that have been reported. For example, another study reported that five out of 12 patients with oral leukoplakia had a complete response.
And finally, another study found that the best therapeutic outcomes were achieved when the lesions were treated with topical PDT twice a week instead of once a week. This again highlights one of the greatest advantages of PDT—that repeated treatments can be safely and effectively administered for those who do not initially show a complete response, thus helping to ensure treatment success.
Of course, if the ultimate goal is to reduce one’s risk of oral cancer, it is also necessary for someone with oral leukoplakia to avoid tobacco, alcohol, and other risk factors for the disease. No amount of PDT will be able to ward off oral cancer if the causes of that cancer continue to be a regular part of one’s lifestyle.
Sources
Vohra F, Al-Kheraif AA, Qadri T, Hassan MI, Ahmed A, Warnakulasuriya S, Javed F. Efficacy of photodynamic therapy in the management of oral premalignant lesions. A systematic review. Photodiagnosis Photodyn Ther. 2015 Mar;12(1):150-9
Kübler A, Haase T, Rheinwald M, Barth T, Mühling J. Treatment of oral leukoplakia by topical application of 5-aminolevulinic acid. Int J Oral Maxillofac Surg 1998;27:466-9.
Chen HM, Yu CH, Tsai T, Hsu YC, Kuo RC, Chiang CP. Topical 5-aminolevulinic acid-mediated photodynamic therapy for oral verrucous hyperplasia, oral leukoplakia and oral erythroleukoplakia. Photodiagnosis Photodyn Ther 2007;4:44-52.
Pietruska M, Sobaniec S, Bernaczyk P, Cholewa M, Pietruski JK, Dolińska E, Skurska A, Duraj E, Tokajuk G. Clinical evaluation of photodynamic therapy efficacy in the treatment of oral leukoplakia. Photodiagnosis Photodyn Ther. 2014 Mar;11(1):34-40.
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