The abscopal effect refers to the ability of localized radiation to trigger systemic antitumor effects. Over the past 50 years, reports on the abscopal effect arising from conventional radiation have been relatively rare. However, with the continued development and use of immunotherapy strategies incorporating radiotherapy with targeted immunomodulators and immune checkpoint blockade, the abscopal effect is becoming increasingly relevant in less immunogenic tumors such as breast cancer. Here, we review the mechanism of the abscopal effect, the current preclinical and clinical data, and the application of the abscopal effect in designing clinical trials of immunotherapy combined with radiotherapy in breast cancer.
Background. Conflicting data exist regarding optimum local therapy for early-stage triple-negative breast cancer (TNBC). We examined outcomes according to local treatment type in a large cohort of node-negative TNBC patients. Methods. A total of 1,242 consecutive patients with TNBC treated at a single institution from 1999 to 2008 were identified. Of these, 646 with pathologic stage T1-2N0 TNBC underwent breast-conserving therapy (BCT) (N = 448) or total mastectomy (TM) without postmastectomy radiation (N = 198) and comprised the study population. Locoregional recurrence (LRR), distant metastasis (DM), and overall recurrence were investigated with a competing risk analysis using Gray's test and multivariable Fine and Gray competing risk regression. Overall survival was assessed using standard Kaplan-Meier methods and a Cox proportional hazards analysis. Results. Median follow-up was 78.3 months (range 1-156). Eight-one percent of patients received adjuvant chemotherapy. TM patients were younger, were more likely to have lymphovascular invasion, and had larger tumors than patients undergoing BCT (all P B 0.05). The 5-year cumulative incidence of LRR was 4.2 and 5.4 % for patients undergoing BCT and TM, respectively. There was no significant difference in LRR, DM, overall recurrence, disease free survival, or overall survival between groups on univariate analysis, or after adjusting for other variables in multivariate models. Lack of chemotherapy and high tumor stage independently predicted for decreased overall survival (both P \ 0.001). Conclusions. A low, 5-year risk of LRR (4.7 %) was achieved in a large group of women with T1-2N0 TNBC treated with multimodality therapy. BCT was as equally effective as TM for local and distant control.The poor prognosis of triple-negative breast cancer (TNBC) relative to other biologic subtypes of breast cancer has been well established during the past decade.
PurposeA joint American Society of Clinical Oncology, American Society for Radiation Oncology, and Society of Surgical Oncology panel convened to develop a focused update of the American Society of Clinical Oncology guideline concerning use of postmastectomy radiotherapy (PMRT).MethodsA recent systematic literature review by Cancer Care Ontario provided the primary evidentiary basis. The joint panel also reviewed targeted literature searches to identify new, potentially practice-changing data.RecommendationsThe panel unanimously agreed that available evidence shows that PMRT reduces the risks of locoregional failure (LRF), any recurrence, and breast cancer mortality for patients with T1-2 breast cancer with one to three positive axillary nodes. However, some subsets of these patients are likely to have such a low risk of LRF that the absolute benefit of PMRT is outweighed by its potential toxicities. In addition, the acceptable ratio of benefit to toxicity varies among patients and physicians. Thus, the decision to recommend PMRT requires a great deal of clinical judgment. The panel agreed clinicians making such recommendations for individual patients should consider factors that may decrease the risk of LRF, attenuate the benefit of reduced breast cancer-specific mortality, and/or increase risk of complications resulting from PMRT. When clinicians and patients elect to omit axillary dissection after a positive sentinel node biopsy, the panel recommends that these patients receive PMRT only if there is already sufficient information to justify its use without needing to know additional axillary nodes are involved. Patients with axillary nodal involvement after neoadjuvant systemic therapy should receive PMRT. The panel recommends treatment generally be administered to both the internal mammary nodes and the supraclavicular-axillary apical nodes in addition to the chest wall or reconstructed breast.Electronic supplementary materialThe online version of this article (doi:10.1245/s10434-016-5558-8) contains supplementary material, which is available to authorized users.
By using clinicopathologic features, clinicians delivered PMRT to a select group of patients with T1-T2 tumors and 1 to 3 positive ALN, resulting in similarly low rates of 5-year LRR. Among patients not receiving PMRT, age ≤50 years and LVI were associated with increased LRR rates and warrant PMRT consideration.
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