Investigation of carcinogenic effects of in Vitro Argon and CO2 laser exposure of fibroblasts

CO2 laser resurfacing and photocarcinogenesis: An experimental study

BACKGROUND AND OBJECTIVES

To examine whether carbon dioxide (CO2) laser treatment has a carcinogenic potential or may influence ultraviolet (UV)-induced carcinogenesis.

STUDY DESIGN/MATERIALS AND METHODS

Hairless mice (n = 211) were treated with a Sharplan CO2 laser with FeatherTouch scanner. Simulated solar irradiations were administrated either pre-operatively or pre- and post-operatively. Weekly clinical assessments of skin tumors were performed blinded during the entire observation period of 12 months.

RESULTS

No tumors appeared (a) in mice just treated with CO2 laser, (b) in mice exposed to UV irradiation only before CO2 laser treatment or (c) in untreated control mice. Tumors developed in CO2 laser treated mice that were exposed to UV-irradiation both pre- and post-operatively and in UV-irradiated control mice. The time to first, second, and third tumors ranged from 18 to 20 weeks and no significant differences were demonstrated.

CONCLUSIONS

CO2 laser treatment does not have a carcinogenic potential in itself, nor does CO2 laser treatment influence UV-induced carcinogenesis.

Copper vapor laser and photocarcinogenesis in hairless mice

BACKGROUND AND OBJECTIVE

Port wine stains are commonly located on UV-exposed skin areas. We therefore examined the long-term interaction between UV radiation and copper vapor laser light (578 nm, yellow light) and whether the thermal influence from laser light had a carcinogenic potential itself.

STUDY DESIGN/MATERIALS AND METHODS

The study was conducted in lightly pigmented hairless hr/hr C3H/Tif mice and included 8 groups of 17-20 mice. Intensities of 0.5, 1.0, and 1.4 W were used, corresponding to calibrated Hexascan fluences of 15.9, 31.8, and 44.6 J/cm2. Beam diameter was 1 mm and pulse duration 250 msec. UV irradiation of the mice was performed 4 days weekly and started the day after laser treatment. The UV simulated solar ultraviolet radiation can from one Phillips TL 12 and five Bellarium-S SA-1-12 tubes. The daily dose was 1.3 J/cm2, equivalent to 2.1 B-MED.

RESULTS

No tumors appeared in groups receiving laser light only. The time to first (P < 0.01), second (P < 0.01), and third (P < 0.02) tumor was significantly delayed in the group treated with 1.4 W before UV irradiation (P < 0.01) compared with those receiving UV radiation only. No significant differences could be demonstrated for the groups treated with 0.5 and 1.0 W.

CONCLUSION

One laser treatment with the copper vapor laser did not accelerate UV-induced photocarcinogenesis, and the laser exposure did not have a malignant potential itself.

Carbon dioxide laser surgery of oral leukoplakia

Oral leukoplakia is a precancerous lesion of the oral mucosa. The risk of malignant transformation depends on the clinical and histologic classification and the location of the lesion. For a nonhomogeneous leukoplakia, this risk is 23.4% to 38.0%. In the presence of epithelial dysplasia, the possibility of malignant transformation is 36.3% to 43.0%. Leukoplakia is limited to the epithelium, so a selective removal of this part of the mucosa seems to be the best preventive treatment. Carbon dioxide laser surgery accomplishes a superficial removal by evaporation. A total of 70 patients with 103 oral leukoplakias were treated with carbon dioxide laser evaporation. This resulted in an excellent wound healing with virtually no scarring. The patients were followed up during a period of up to 12 years (mean 5.3 years), showing a cure rate of 90%.

Abnormal epidermal changes after argon laser treatment

A 26-year-old woman with a congenital port-wine stain on the forehead was treated three times at 2-month intervals with an argon laser. Six months after the last treatment, moderate blanching and mild scaling confined to the treated area was observed. A biopsy specimen of the treated area revealed a significant decrease in ectatic vessels. However, epidermal changes similar to those of actinic keratosis with disorganized cell layers and marked cytologic abnormalities were seen. Analysis of peripheral blood lymphocytes for a defect in DNA repair was negative. Multiple, argon laser-induced photothermal effects may be responsible for the changes observed in our case and may lead to premalignant epidermal transformation.