Nd: YAG interstitial laser thermotherapy in the treatment of breast cancer.

BACKGROUND AND OBJECTIVE: "Minimal treatment strategy" is desirable in certain breast cancer patients. The main objective of the present study is to examine the use of interstitial laser thermotherapy (laserthermia) for this purpose. STUDY DESIGN/MATERIALS AND METHODS: Thirty-five patients with primary breast cancer were treated with laserthermia using the Nd:YAG (1,064 nm) pulse-wave laser. In 28 patients, laserthermia was performed before radical resection, and in seven patients it was the only invasive treatment. RESULTS: One gaseous rupture of tumor occurred at 3 Watts. The diameter of single focus of laser-induced damage after 1-2 Watts was less than 1 cm, and after 2.5-6 Watts it reached 1.5-2.5 cm. Of seven patients treated without surgery, local tumor control was achieved in five, and in three stage I-III patients disease-free survival followed for 19-60 months. After laserthermia plus surgery, 3-year disease-free survival was 27% in premenopausal and 92% in menopausal patients. CONCLUSIONS: It seems that laser destruction of relatively small primary breast cancer is possible. Provisionally, laserthermia should not be used in premenopausal patients.

[Estimation of the extent of malignant tumor damage in laser interstitial thermal therapy]. / Raschet razmerov zony porazheniia zlokachestvennoi opukholi pri lazernoi interstitsial'noi termoterapii.

A one-dimensional mathematical model has been developed for the thermal malignant tumor damage caused by Nd:YAG laser infrared radiation through a light guide. The model is based on the transient thermal conduction equation and considers the effects of intratissue blood flow, tissue radiation absorption, phase transition (evaporation) and varying tissue thermal tolerance. Examples of computer-aided numerical calculations are presented. A relation of the sizes of the specific areas of thermal tumor tissue damage to the magnitude of radiation, treatment time, blood flow rates, and tissue thermal tolerance is shown. The calculation results are compared with the experimental data obtained on laboratory animals. The calculation model and programme are proposed to be clinically used while planning laser interstitial thermal therapy for human malignant tumors.