Local Accelerated Radionuclide Breast Irradiation: Avidin-Biotin Targeting System

Abstract

Breast cancer remains the most common cancer in women in the developed world and the most frequent cause of cancer-related death among women worldwide [1]. In 2010 in the United States, the estimated number of new cases of breast cancer was 207,090 (28 % of all cancer in women), with 39,840 expected deaths (second cause of death after lung and bronchus carcinoma) [2]. Fortunately, thanks to the screening campaigns carried out in the Western countries, breast cancer can be treated in its early phase. The conventional surgical treatment for early breast cancer consists of either a mastectomy or breast conserving surgery (BCS), often accompanied by axillary dissection or sentinel node biopsy. If BCS is performed, whole breast external beam radiotherapy (EBRT) with doses around 50–60 Gy remains the gold standard for local control. The benefit of postoperative radiotherapy is well known since the completion of few prospective randomized trials conducted in the years 1976–1990, which compared conservative surgery and radiation with conservative surgery alone. Several clinical trials compared also breast conservative surgery (BCS) alone vs. BCS followed by whole breast (WB) EBRT: 10–35 % of women receiving BCS alone showed locoregional recurrence, whilst it occurred only in 0.3–8 % of women after BCS plus WB-EBRT (follow-up range: 39–102 months), although both treatments produced the same 10-year overall survival rates [3]. However, there is some recent evidence that lack of radiotherapy is associated with an increased hazard ratio for death [4]. Current accepted treatment protocol takes advantage of the above experiences and consists of BCS, usually accompanied by axillary node dissection or sentinel node biopsy. If BCS is performed, it is almost always accompanied by postoperative regional radiotherapy; 2 Gy per day delivered five times a week for 6–8 weeks, for a total dose of 50–60 Gy to eliminate microscopic cancer foci remaining after surgery [5]. A substantial benefit of an additional boost with 16 Gy to the tumor bed was recently confirmed by the EORTC [6] particularly in premenopausal women.