Temperature rise in biological tissue during Nd:YAG laser irradiation.

Few data are available about temperature distribution in tissue during Nd:YAG laser irradiation. To study the heat distribution that produces tissue coagulation, we used a thermographic camera aimed orthogonally to the laser beam axis to obtain thermal maps. Immediately after surgical resection, specimens of human stomach were irradiated near the resected edge, and the heat emitted sideways was detected by an infrared image system. A magnifying lens mounted on the camera enabled us to obtain 0.1 mm spatial resolution of the isothermic curves. The thermal analysis showed that the maximum depth where the increase in temperature reached 25 degrees C (corresponding to a coagulation temperature of about 60 degrees C) was never greater than 3 mm, irrespective of the power and exposure time used. Moreover, the bidimensional thermal maps showed that the temperature did not decrease in a purely exponential fashion along the beam axis, but reached a maximum at about 1 mm beneath the surface. This fact, which confirms the decrepitation theorem, could explain the explosion inside the tissues observed in surgical application of the Nd:YAG laser.

Hyperthermal effects in phototherapy with hematoporphyrin derivative sensitization.

Although the photochemical reaction of hematoporphyrin derivative (HpD) appears to play a major role in cytotoxic activity, the hyperthermal contribution to tumor destruction has not yet been clarified. We investigated its role in the effectiveness of laser photoradiation therapy using MS-2 sarcoma transplanted into the hind pad of BALB/c mice as the experimental model. Mice received HpD i.v., 25 mg/kg - 24 h before exposure to light delivered from a dye laser or Nd-YAG laser, or before warming in a thermostated bath. Since our aim was not to cure the tumor, the treatment response was evaluated only as inhibition of tumor growth at different days after treatment. Our results support the view that in laser photochemotherapy the hyperthermia produced by irradiation and the photodynamic effect mediated by HpD could contribute to tumor destruction. Moreover, a synergistic interaction between the photodynamic effect and heat was observed in this experimental model.

Laser phototherapy following HpD administration in superficial neoplastic lesions.

We report our preliminary clinical experience with hematoporphyrin derivative (HpD) injection and argon or dye laser irradiation for the treatment of 61 surface neoplastic lesions in 7 patients. Forty-three sites were multiple basal cell carcinoma in 5 patients, and the remaining 18 were cutaneous and subcutaneous recurrent breast carcinoma after mastectomy in the thoracic wall. The patients were selected on the basis of the lack of indication for conventional therapeutic modalities. The selection of irradiation procedures and laser source was based on the thickness of the lesion and extension of the disease. The photochemical reaction between HpD injected i.v. at a dose of 3 mg/kg body weight and the laser beam at a dose of 60 to 120 J/cm2 resulted in 75% favorable responses at the treated sites. Optimal therapeutic effects appeared to be critically dependent on total light dose and tumor infiltration patterns. The phototherapeutic technique proved to be effective in selected cases of neoplastic lesions, especially when conventional treatment modalities were poorly indicated or contraindicated.

CO2 lasers: beam patterns in relation to surgical use.

According to surgeons operating with a variety of CO2 lasers available at the National Cancer Institute of Milan (Coherent, Sharplan, Valfivre), these lasers have different cutting and coagulation properties. To identify what physical parameters might corroborate the subjective impression of the surgeons, a comparative study of the crater forms in perspex samples was performed. Perspex was chosen for its thermal properties (in fact, its thermal conductivity and diffusivity are similar to those of organic tissue) and because it allowed good visualization and measurement of crater characteristics. Depth of penetration, crater diameter, and extension of thermal damage were measured against power, focal length, and exposure time for each CO2 laser model. These results can be used as an index of behaviour of different surgical lasers. It appears that for fully characterizing the interaction of surgical lasers with the sample, it is necessary to specify either power, focal length, exposure time, or beam mode.

The outpatient-procedure effectiveness of laser treatments in oncology.

The outpatient procedure of CO2 laser surgery has been recently integrated into the routine activity of the National Cancer Institute, Milan. Specific operative protocols that are codified for laser outpatient selection after adequate staging by pathology are presented. Specific indications for gynecologic disease (preneoplastic disorders, CIN, VAIN, and VIN), and general-surgery neoplastic disorders (soft tissue sarcomas, lip and oral cavity lesions, breast lesions) are described. Details of the safety procedures, rules of application, laser instrumentation accessories and wattages, both with vaporization and excisional technique, are reported. An overall rate of 30% out of the 4,000 cases treated yearly are selected for laser treatment procedures on the basis of the evaluation of real advantages. The general advantages of laser surgical applications such as reduction of bleeding and postoperative pain, early and late complications; no-touch method; and patient acceptability--have been emphasized in the routine outpatient procedures. Reduction of the total costs and of the waiting list for hospitalization by the new procedures are finally considered.

Laser oncology in Italy: experimental research and clinical applications at the National Cancer Institute, Milan.

CO2, Nd:YAG, and argon lasers have been used for 5 years for experimental and clinical procedures at the National Cancer Institute of Milan under the auspices of the National Research Council. Experimental data regarding tumor cell spread through lymphatic and hematic channels and cell viability in the fumes after CO2 laser irradiation are reported. New advantages in the combined treatment modalities have been demonstrated, since the synergism between the low power argon laser beam and chemotherapeutic agents (anthracyclines) was assessed on cell cultures and the least toxic and the most effective doses of the drugs were identified. Due to the optical properties of the laser beam, physical measurements of the delivered energy and mathematical calculation of the energy per tissue volume unit to be ablated increase the precision in microsurgery especially when conservative managements are indicated. Main applications in surgical oncology, and comparison versus conventional methods, both with vaporization and excisional techniques, according to specific therapeutic protocols, in general surgery, otolaryngology, gynecology, and endoscopy, even on an outpatient basis, are finally illustrated in a series of 600 cases.

Impact of cancer, type, site, stage and treatment on the nutritional status of patients.

This study analyzed the nutritional status of cancer patients in relation to type and site of origin of the tumor, stage of disease, and previous chemical or radiation therapy. The analysis was performed on 321 patients (280 with cancer and 41 controls). The nutritional parameters included per cent of weight loss, anthropometric indices (arm circumference, triceps skinfold, arm muscle circumference), creatinine-height index, serum protein, albumin, total iron binding capacity and cholinesterase, C3 and C4 components of complement, total peripheral lymphocytes, and skin tests. The statistical comparison between patients with different tumors and controls, between patients with different stages of the same tumor, and between patients treated with or without previous chemical or radiation therapy led to the following conclusions: 1) malnutrition is mainly related to the type and site of origin of the tumor and, in the early stages of disease, is more pronounced in patients with cancer of the esophagus and stomach; 2) except in patients with breast and cervix cancer, malnutrition gets more severe as the disease becomes advanced; 3) chemical or radiation therapy has a variable impact on the nutritional status, but in selected patients it causes a drop in body weight, arm circumference, arm muscle circumference, and peripheral lymphocytes; 4) body weight, cutaneous delayed hypersensitivity and serum albumin are the most commonly altered parameters.

Effect of supportive intravenous hyperalimentation on the nutritional status of cancer patients.

The effect of intravenous hyperalimentation on the nutritional status of 84 cancer patients treated at the Istituto Nazionale Tumori, Milan, has been evaluated. The body weight increased in 78% of patients, mid upper arm circumferance in 93%, triceps skinfold in 73%, mid upper arm-muscle circumference in 73%, creatinine/height index in 30%, serum albumin in 32%, transferrin in 35%, total peripheral lymphocytes in 38%. Lymphocyte blastogenesis increased in 74% of the patients examined and skin tests were converted from negative to positive in about 20% of patients. In addition 8 our of 18 patients responsive to IVH benefited from chemotherapy and/or radiotherapy indicating that the nutritional repletion of the host did not significantly affect the growth of the tumor. These findings support the opinion that neoplastic cachexia may depend partially on malnutrition and can be often reversed by IVH. Moreover, IVH might have an adjunctive role as potentiator of chemotherapy which however must be confirmed by clinical trials.

[Parenteral hyperalimentation in patients with advanced neoplastic disease (author's transl)]. / Iperalimentazione parenterale nei pazienti con neoplasia avanzata

Two groups of patients suffering from advanced neoplastic disease were fed parenterally for a period ranging from 1 to 16 weeks. The parameters considered were: weight change, serum albumin level, lymphocyte transformation test and serum immunoglobulin level. There were 23 patients in one group and 21 patients in the other. Regimens included for group I: saline solution (1000-1500 ml), glucose (100-150 g) and amino acids (15-30 g) per day; for group 2: 40-50 Cal/kg per day (dextrose about 15 g/kg per day), about 2 g of amino acids/kg/day and about 40-50 ml water/kg/day. In addition, 13 patients underwent both treatments sequentially. All the Group I patients lost weight (1.3 kg/week); while out of 23 patients in Group 2, 15 gained weight, 2 remained unchanged and 6 continued to lose weight, but to a lesser rate than before hyperalimentation (the average weight gain was 1.1 kg/week). Serum albumin levels decreased in 19 out of 25 patients in Group I and increased in 14 out of 26 patients of Group 2. Initial values of the lymphocyte blast transformation test were very low in both groups of patients, and an increase was observed only in patients treated by hyperalimentation. The increase was more evident in patients who were not under antiblastic treatment. Changes in serum immunoglobulin levels were not significant. The authors conclude that malnutrition plays a very important role in neoplastic cachexia and can be improved by parenteral hyperalimentation. Although it is possible that in the near future hyperalimentation and conventional neoplastic therapies will play complementary roles in treatment of advanced neoplastic disease, malnutrition is still the specific indication for intravenous hyperalimentation.