The methods of tumors bed localization and boost dose delivery during conservative breast cancer treatment

Breast-conserving therapy (BCT) consists of whole breast irradiation, usually at a dose of 50 Gy, and a boost dose of 10-20 Gy to the tumor bed. A decreased risk of local recurrence in patients administered the boost has been confirmed in a large randomized trial. The precise localization of the tumor bed (boost dose volume) is often difficult, while the recommended intraoperative placement of metal markers into the tumor cavity walls is not always performed. It is more common to localize the tumor bed using other available data, such as tumor site at the initial clinical examination or mammograms, skin scar localization, postoperative induration of the mammary gland, and histological examination. All these methods are considered less exact than the volume outlined by surgical clips. Alternative approaches allowing precise delivery of radiotherapy to the tumor bed are intraoperative placement of brachytherapy catheters or intraoperative external beam irradiation. In this review we discuss the methods used of determining the tumor bed and the different radiotherapy boost techniques used in breast cancer patients managed with BCT. We also present guidelines of the American Brachytherapy Society for the use of brachytherapy as a boost method. (author)