The novel technique of delivering targeted intraoperative radiotherapy (Targit) for early breast cancer.

AIM: We believe that conservative treatment of early breast cancer may not require radiotherapy that encompasses the whole breast in all patients. We have developed a novel therapeutic approach that allows targeted intraoperative radiotherapy (Targit) to be safely and accurately delivered in a standard operating theatre. We are currently recruiting for a randomized trial testing whether Targit can replace the whole 6 weeks of post-operative radiotherapy after breast conserving surgery. METHODS: This paper describes the operative technique. It employs a miniature electron-beam-driven X-ray source called INTRABEAM (PeC) that emits soft X-rays (50 kV) from within the breast. The X-rays are emitted from the tip of a 10 cm x 3.2 mm diameter probe, that is enclosed in a spherical applicator (available in 2.5-5 cm diameter sizes), which in turn is inserted in the tumour bed and intraoperative radiotherapy is delivered in about 25 min. The prescribed dose is 5 and 20 Gy at 1 cm and 0.2 cm respectively, from the tumour bed. RESULTS: The biologically effective dose is 7-53 Gy for alpha/beta=10 and 20-120 Gy for alpha/beta=1.5. The quick attenuation of the radiation reduces the damage to normal tissues and allows radiotherapy to be delivered in a standard operating theatre. Tungsten impregnated rubber sheets, cut to size, are placed on the chest wall to protect the heart/lungs and over the wound to stop stray radiation. The skin dose is monitored with thermoluminescent detectors (TLDs). After wide local excision of the tumour and good haemostasis, a spherical applicator is inserted in the tumour bed and the target breast tissues are wrapped around it with a purse-string suture. Thus, true conformation of the target around the applicator source is achieved in real time. CONCLUSION: As a tumour bed boost, this technique has the potential to reduce local recurrence by avoiding geographical misses and achieving excellent dosimetry. In patients with low risk of local recurrence, it has the potential to replace the full 6 weeks of post-operative radiotherapy with considerable implications to patients and hospitals.