STEREOTAXIC USES BEYOND CORE BIOPSY - MODEL DEVELOPMENT FOR MINIMALLYINVASIVE TREATMENT OF BREAST-CANCER THROUGH INTERSTITIAL LASER HYPERTHERMIA

Light of a Nd:YAG laser presented through a fiberoptic cable to a diff using tip can be adapted to mammographic stereotactic instruments now used for core biopsy in the hyperthermic endoablation of breast cancer . This approach to cancer destruction extends breast preservation to t he point of no observable surface skin change. The initial analysis ch aracterizes the effects of laser endohyperthermia in a physical model as well as in tissue, both ex vivo and in vivo, to create a reliable t echnique that will lead to human trials. A fiberoptic cable with a dif fusing quartz tip placed deep within soft tissue can pass light of a n eodymium laser and consequent thermal energy for the destruction of su rrounding soft tissues. Because breast cancer occurs with greatest fre quency in the involuted breasts of women more than 50 years of age and because this tissue is predominantly fibro-fatty in nature, our work has concentrated on model development and the determination of heat di stribution and destruction of fat and fibro-fatty tissue. Following th e development of a physical model, time-temperature courses were found to be similar in ex vivo human breast tissue and subcutaneous porcine fat. This led to in vivo porcine studies that confirmed similar time- temperature courses. For tissues brought to a range of 60 degrees C to 80 degrees C and sustained for the better part of 20 minutes, gross a nd histological analyses reveal complete destruction over a 1 1/2 cm r adial region around the laser tip. This approach offers great promise for the treatment of stereotactically biopsied small T1 breast carcino mas.