Interstitial laser thermotherapy (ILT) of breast cancer.

Aim: To find out if ILT can be used as radical treatment of breast cancer.
Method: Twenty-four patients, aged 39-84 (mean 61), with invasive breast cancer were treated with ILT. All underwent mammography, ultrasound and core biopsy before treatment. The tumour was an invasive ductal carcinoma in 15 patients, a lobular carcinoma in eight and lobular-ductal cancer in one. Average tumour diameter was 14 mm on ultrasound (5-35). Patients were treated in the outpatient clinics under local anaesthesia. Probes were placed under ultrasound guidance, in 19 patients, and ILT was performed with a diode laser at a steady-state temperature of 48 degrees C for 30 min using temperature feedback control. Standard surgical excision was performed 12 (4-23) days after ILT and was preceded by Doppler ultrasound.
Results: Treatment-induced necrosis of invasive cancer was 33% (range 0-100) and was complete in three patients. At follow-up before surgery, the extent of laser damage could not be judged with ultrasound, although abolished tumour blood flow was demonstrated after treatment resulting in large necroses. Efficacy of treatment varied negatively with tumour size. The inefficacy of ILT was mainly due to the underestimation of tumour size by mammography and ultrasound and the shortcomings of these methods to demonstrate tumour borders, tumour irregularity and carcinoma in situ (CIS). ILT was well tolerated. Five patients had breast tenderness, and three patients had pain, during the first day after treatment. Small skin necroses were observed in two patients.
Conclusion: Small breast cancers can be treated radically with ILT. The method may become useful in the treatment of breast cancer but needs further refinement, even for small well-defined breast cancers, if it is going to be employed for radical treatment.