Interception of lymphatic drainage by Nd: YAG laser irradiation in rat urinary bladder

Laser surgery as a treatment for oral leukoplakia

Various treatment procedures for oral leukoplakia have been reported. However, after some treatments, oral leukoplakia show recurrence and/or malignant transformation, even following complete resection. Furthermore, patients with oral leukoplakia may develop new lesions in other oral cavity locations. Laser surgery for oral mucosal lesions has been reported to have many advantages, and it is widely used in the treatment of oral leukoplakia. In previous studies, recurrence and malignant transformation from the lesion have occasionally been observed following laser surgery. We reviewed the records of oral leukoplakia patients treated with laser surgery to assess its clinical usefulness. It has been reported that the rate of recurrence was 7.7-38.1%, while malignant transformation was 2.6-9% for oral leukoplakia treated with laser surgery. In the present study, there was 29.3% recurrence and 1.2% malignant transformation after laser surgery. This was similar to previous findings. This suggests that non-homogeneous leukoplakia on nonkeratinized epithelia, i.e. the tongue mucosa has a high risk for malignant transformation, so lesions should be excised after detecting abnormal epithelia using vital tissue staining. The wound healing process after laser surgery was satisfactory and no significant complications were observed. Management of oral leukoplakia prevents not only recurrence and malignant transformation, but also postoperative dysfunction: laser surgery is an excellent procedure that is able to overcome these problems.

Soft tissue application of lasers

Despite increasing numbers of veterinarians incorporating lasers into their clinical practices, little information has been published about laser clinical applications in soft tissue surgery. This article reviews soft tissue interaction, describes laser equipment and accessories commonly marketed to veterinarians, and discusses clinical applications of the carbon dioxide laser in a systems-based approach. A table of recommended laser tips and settings based on the authors' experiences using a carbon dioxide laser (AccuVet Novapulse LX-20SP, Bothell, WA) is provided.

Clinical assessment of laser monotherapy for squamous cell carcinoma of the mobile tongue

OBJECTIVE

Laser monotherapy for squamous cell carcinoma of the mobile tongue treated with CO2 laser was carried out on 18 cases between 1979 and 1997.

MATERIALS AND METHODS

Three cases recurred after laser surgery. As a subsequent therapy, radiotherapy was performed on two of them and laser surgery was repeated on the remaining one. No recurrences were found in the two patients who died from other diseases after laser surgery.

RESULTS

The cure rate of primary tumors was 83.3%. One patient had subsequent metastasis after laser surgery. The rate of recurrence and subsequent metastasis was compared between a group of patients treated with laser surgery and a group treated with radiotherapy (interstitial implant). No differences were found in the rate of recurrence between the two groups. While 22 of 52 patients had a subsequent metastasis in the group treated with interstitial implant, only one patient had it in the group treated with laser surgery. There was a statistical difference between these two groups (p < 0.01).

Nd-Yag laser treatment of bladder tumours

Between 1989 and 1992, 116 patients suffering from bladder tumours had been treated with Nd-Yag laser. In 74 cases only laser treatment was applied, in 42 cases laser treatment was combined with transurethral resection (TUR). The patients were in phases Ta, T1 or T2 and in the majority of them histological examination did not reveal Grade 3. No considerable complications, e.g. perforation of the bladder or severe haemorrhages, were observed during laser treatment. After laser and TUR+laser treatment, respectively, relapses occurred in 16-19% of the cases, considerably less frequently than after treatment with only TUR.

Randomized trial of laser scalpel for modified radical mastectomy

The efficacy of a contact neodymium yttrium-aluminium-garnet laser scalpel was assessed during breast surgery. Forty consecutive women undergoing modified radical mastectomy were randomized to operation performed with a conventional or laser scalpel. The laser scalpel was associated with a significant reduction in mean operative blood loss (149 versus 421 ml; 95 per cent confidence interval of difference 176-368 ml, P < 0.001), but the mean operating time was longer (105 versus 80 min; 95 per cent confidence interval of difference 16-34 min, P < 0.001). No significant differences were found in the volume of postoperative wound drainage, incidence of axillary seroma, postoperative pain score or time to return of shoulder mobility. Use of a laser scalpel in breast surgery cannot be recommended.

Optical properties of rat liver and tumor at 633 nm and 1064 nm: photofrin enhances scattering

Predicting the effects of photodynamic therapy (PDT) and Nd: YAG laser coagulation requires knowledge of the light distribution in tumor and surrounding tissue. Therefore, absorption and scattering coefficients and the average cosine of the scattering angle (the anisotropy factor) were measured in rat liver and tumor at 632.8 and 1064 nm. A syngenic colon adenocarcinoma CC531 was implanted subcutaneously in two groups of 7 Wag/Rij rats. In one group Photofrin was administered 5 mg/kg intravenously 48 h before determination of optical properties. Two months after inoculation, samples were taken from tumor and liver and optical properties determined using indirect methods with two integrating spheres. The absorption coefficient was larger in liver than in tumor at 632.8 nm (P < 0.0005), whereas the scattering coefficient was larger in tumor than in liver at 1,064 nm (P < 0.05). Addition of Photofrin increased the scattering coefficient in liver and in tumor at both wavelengths (P < 0.025) and decreased the anisotropy in tumor (P < 0.025), suggesting that for modelling the dosimetry of PDT the optical properties of photosensitized tissue should be used.

Treatment of experimental liver metastases with a noncontact neodymium: YAG laser

The extent of tumor and liver damage after treatment with the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser was investigated in a rat tumor model. Colon carcinoma CC531 was implanted in the liver and treated with 60 J (14 tumors), 120 J (15 tumors), or 180 J (12 tumors) at a power setting of 20 W. To assess the effects upon the tissues three animals were sacrificed immediately after treatment and 1, 2, 4, and 8 days later. Sections from the tumor sites were evaluated by light microscopy and the maximal depth and width of different zones of tissue damage were measured. Laser effects could be determined most accurately on Days 1 and 2 after treatment. Multiple linear regression analysis of the data indicated a linear relationship between laser energy and depth of tumor damage (P less than 0.01). The results of this study show the potential of the Nd:YAG laser to produce tumor coagulation necrosis with minimal liver necrosis.

Water-jet-cooled Nd:YAG laser coagulation: selective destruction of rat liver metastases

The photocoagulating properties of the water-jet-cooled Nd:YAG laser (1,064 nm) have been studied in a rat tumor model. A colon carcinoma CC531 was implanted in the liver; 20 days after inoculation, laser therapy was performed with 600 J, 850 J, 1,200 J, 1,700 J, or 2,400 J at a power setting of either 10 or 20 W. Liver damage was determined in tissue specimen on day 1 after treatment and by serum levels of alanine aminotransferase and aspartate aminotransferase on day 1 and 2. Tissue specimen of day 36 were used to evaluate tumor remission. Liver function was assessed by antipyrine clearance on day 2. Light microscopic examination on day 1 showed coagulative necrosis up to 10 mm in diameter at 1,700 J and 20 W. At 20 W, liver damage was 22% larger than at 10 W (P = 0.0001). A significant relationship was found between laser energy and liver damage with complete tumor destruction in all animals at 2,400 J. No deterioration in liver function was found. The results of this study show the ability of the water-jet-cooled Nd:YAG laser to produce tumor coagulation necrosis with minor liver damage.

Installation and use of a neodymium-YAG laser in a urology department

We report our experience in setting up a urological laser unit. An operating theatre was upgraded to include the required safety features and a neodymium-YAG laser was installed. A preliminary study using cadaver bladders was performed to establish the technique of cystoscopic laser application. We treated 55 bladder tumours in 12 patients by laser coagulation, with total destruction of 54 tumours and no serious complications; 6 patients developed recurrent tumours. Twenty-one patients underwent surgery with the contact laser scalpel. The instrument proved slow but effective, with excellent haemostasis and almost painless wounds. Healing was delayed in 2 cases but there were no wound infections. All wounds healed with good cosmetic scars. The neodymium-YAG laser is an effective means of destroying superficial non-invasive bladder tumours endoscopically and can also be used in conjunction with a laser scalpel for open surgery.

Current laser applications in general surgery

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Preliminary report on use of the neodymium-YAG laser in plastic surgery

Thirty-four patients with 57 cutaneous lesions have been treated with the Nd:YAG laser under an experimental protocol over a year of study. The majority of treatments were done on an outpatient basis under local anesthesia. Capillary/cavernous hemangiomas of the oral cavity responded well, but hemangiomas of infancy responded poorly. Hypertrophic scars and keloids responded well only in conjunction with steroid treatment. Epistaxis in patients with hereditary hemorrhagic telangiectasia responded well for 4-5 months and then recurred. Areas with thin skin or mucosa have the potential for full-thickness injury with complications of scar, bony exposure, or septal perforation.