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

Introduction:We believe that conservative treatment of earlybreast cancer may not require radiotherapy that encompasses the whole breast.We present here the clinico-pathological basis for this view, as well as anovel therapeutic approach that allows intra-operative radiotherapy to besafely and accurately delivered to the target tissues in a standard operatingtheatre.The rationale:Whole-organ analysis of mastectomy specimensreveals that 80% of occult cancer foci are situated remotefrom the index quadrant. In contrast, over 90% of localrecurrences after breast conservative therapy occur nearthe originaltumour, even when radiotherapy is not given. Therefore, the remote occultcancer foci may be clinically irrelevant and radiotherapy to the indexquadrant alone might be sufficient.A novel technique:The Photon Radiosurgery System (PRS) is aningenious portable electron-beam driven device that can typically deliverintra-operative doses of 5–20 Gy, respectively, to 1 cm and 0.2 cmfrom the tumour bed over about 22 min. The pliable breast tissue – thetarget – wraps around the source, providing perfect conformalradiotherapy. Being soft X-rays, the dose attenuates rapidly(1/r³), reducing distant damage.Results:In our pilot study of 25 patients (age 30–80 years,T = 0.42–4.0 cm), we replaced the routine post-operative tumour bedboost with targeted intra-operative radiotherapy.There have been no major complications and no patient has developed localrecurrence, although the median follow-up time is short, at 24 months.Conclusion:It is safe and feasible to deliver targetedintra-operative radiotherapy (Targit) for earlybreast cancer. We have begun a randomised trial – the first of its kind– comparingTargitwith conventional six-week course ofradiotherapy. If proven equivalent in terms of local recurrence and cosmesis,it could eliminate the need for the usual six-week course ofpost-operative radiotherapy.