Partial-breast treatment for early breast cancer: emergence of a new paradigm.

Although hailed as a paradigm shift, the breast conservative treatment that emerged in the 1980s was in fact an extension of the Halstedian concept, wherein whole-breast irradiation (WBI) compensated for the limited surgery. Observations that 80-90% of breast recurrences after breast conservative surgery and WBI occur in the tumor bed questions the need for protracted elective WBI, and provides the rationale for accelerated-partial-breast irradiation (APBI) of small cancers without adverse features predisposing to multicentric recurrence. APBI can be given over a week with various external beam, intraoperative or brachytherapy (interstitial or MammoSite) techniques. Since the approval of MammoSite by the US FDA in May 2002, a surge of interest has been evident, with 4,000 cases treated using this technique in the past 2 years. Several phase II APBI brachytherapy studies show that 4 to 7-year breast control rates (95%), survival and cosmetic outcome obtained from more than 600 appropriately selected women are comparable to matched or historic controls receiving WBI. The 2 to 3-year interim results of two ongoing randomized trials do not show any early detriment with APBI. If mature results of randomized trials confirm equivalence of APBI to conventional WBI in selected women, it would mark a paradigm shift and a major advance in treatment. This would allow many more women to opt for breast conservation, resolve the dilemmas regarding chemotherapy and radiotherapy sequencing and perhaps would be more cost effective.