Targeted intra-operative radiotherapy (Targit): An innovative method of treatment for early breast cancer

Introduction: We believe that conservative treatment of early breast cancer may not require radiotherapy that encompasses the whole breast. We present here the clinico-pathological basis for this view, as well as a novel ther apeutic approach that allows intra-operative radiotherapy to be safely and accurately delivered to the target tissues in a standard operating theatre. The rationale: Whole-organ analysis of mastectomy specimens reveals that 80 % of occult cancer foci are situated remote from the index quadrant. In con trast, over 90% of local recurrences after breast conservative therapy occu r near the original tumour, even when radiotherapy is not given. Therefore, the remote occult cancer foci may be clinically irrelevant and radiotherap y to the index quadrant alone might be sufficient. A novel technique: The Photon Radiosurgery System (PRS) is an ingenious por table electron-beam driven device that can typically deliver intra-operativ e doses of 5-20 Gy, respectively, to 1 cm and 0.2 cm from the tumour bed ov er about 22 min. The pliable breast tissue - the target - wraps around the source, providing perfect conformal radiotherapy. Being soft X-rays, the do se attenuates rapidly (alpha similar to1/r(3)), reducing distant damage. Results: In our pilot study of 25 patients (age 30-80 years, T = 0.42-4.0 c m), we replaced the routine post-operative tumour bed boost with targeted i ntra-operative radiotherapy. There have been no major complications and no patient has developed local recurrence, although the median follow-up time is short, at 24 months. Conclusion: It is safe and feasible to deliver targeted intra-operative rad iotherapy (Targit) for early breast cancer. We have begun a randomised tria l - the first of its kind - comparing Targit with conventional six-week cou rse of radiotherapy. If proven equivalent in terms of local recurrence and cosmesis, it could eliminate the need for the usual six-week course of post -operative radiotherapy.