Breast-conserving therapy (BCT), consisting of surgical removal of the primary tumor followed by radiation therapy to the intact breast, is now considered a standard treatment approach for early-stage breast cancer. Increasing numbers of patients are becoming eligible for breast conservation after the diagnosis of breast cancer, due to improvements in early detection and patient awareness. In addition, patients presenting with larger tumors that previously would have required mastectomy may now be eligible for BCT using neoadjuvant chemotherapy to downsize the tumor, followed by local excision and radiation. Data from multiple randomized prospective studies have demonstrated equivalent long-term survival outcomes for BCT compared to mastectomy and the benefit of adding adjuvant radiation therapy after conservative surgery. Furthermore, there are numerous retrospective single-institutional series that support the use of conservative surgery and radiation therapy in early-stage breast cancer. This chapter will discuss the indications and validity of postoperative, whole-breast radiation therapy for noninvasive and invasive cancer, and will address special considerations and future directions for radiation therapy as a component of breast conservation therapy for early-stage breast cancer.
Lobular carcinoma in situ (LCIS) is generally considered a risk indicator for the development of invasive carcinoma, and not a malignancy in and of itself. Although the overall management of pure LCIS remains somewhat controversial, patients are often treated with conservative surgery alone or sometimes mastectomy. In addition, there are substantial data to support the use of tamoxifen for LCIS, to reduce the risk of future invasive breast cancer.1 In patients who undergo surgical excision with pure LCIS histology, the literature on the use of radiotherapy postoperatively is very limited.2,3 After a recent workshop on LCIS conducted by EUSOMA members in London, the group concluded that "there is little data to recommend radiation therapy in the clinical management of LCIS."4 Therefore, based on insufficient data to support its usage, radiation therapy after local excision is not typically utilized in the management of pure LCIS.
For patients who have LCIS as a component of their invasive breast cancer, the decision for BCT should be based on the evaluation of the invasive component alone. If LCIS is present at the surgical margin of an invasive carcinoma, no further re-excision is required so long as the invasive component is completely excised. Despite some conflicting data from single-institutional series,5-7 it is generally accepted that local control does not appear to be compromised with LCIS as a component of invasive cancer. Therefore, BCT is a reasonable treatment option for patients with invasive cancers with associated LCIS, and further excision for margins involved with LCIS alone is not warranted.
Although ductal carcinoma in situ (DCIS) is a noninvasive breast malignancy with an overall good to excellent prognosis, the biological diversity correlates with the variable malignant potential and therefore the risk of local recurrence can be relatively high with surgery alone. In addition, the natural history of recurrent disease can be significantly different ...