Real-World Data: Applications and Relevance to Cancer Clinical Trials.

Randomized controlled trials (RCTs) are the gold standard for comparative-effectiveness research (CER). Since the 1980s, there has been a rise in the creation and utilization of large national cancer databases to provide readily accessible "real-world data" (RWD). This review article discusses the role of RCTs in oncology, and the role of RWD from the national cancer database in CER. RCTs remain the preferred study type for CER because they minimize confounding and bias. RCTs have challenges to conduct, including extensive time and resources, but these factors do not impact the internal validity of the result. Generalizability and external validity are potential limitations of RCTs. RWD is ideal for studying cancer epidemiology, patterns of care, disparities in care delivery, quality-of-care evaluation, and applicability of RCT data in specific populations excluded from RCTs. However, retrospective databases with RWD have limitations in CER due to unmeasured confounders and are often suboptimal in identifying causal treatment effects.

Partial Breast Reirradiation for Patients With Ipsilateral Breast Tumor Recurrence After Initial Treatment With Breast Conservation for Early Stage Breast Cancer.

PURPOSE: Accelerated partial breast irradiation (APBI), including intraoperative radiation therapy (IORT), is an evidence-based treatment option in patients undergoing breast conserving surgery (BCS) for early-stage breast cancer. However, literature regarding reirradiation for patients with ipsilateral breast tumor recurrences (IBTR) is limited. This prospective study assessed the feasibility and efficacy of using APBI in patients who had prior whole breast irradiation. METHODS AND MATERIALS: This was a single institution, prospective study of patients who were previously treated with BCS and adjuvant whole breast radiation. At the time of enrollment, all had unifocal IBTR, histologically confirmed invasive ductal carcinoma with negative margins after repeat BCS. Patients received either IORT in a single fraction at time of BCS or MammoSite brachytherapy twice daily over 5 days. Follow-up data and patient surveys were collected at 1, 3, 6, 9, and 12 months, then annually for at least a 5-year period. RESULTS: From 2008 to 2014, 13 patients were enrolled. Median time to recurrence after initial course of radiation was 12.5 years. Median follow-up after retreatment was 7.8 years. One patient in the IORT group had a subsequent tumor bed recurrence, yielding a local control of 92%. One patient had distant recurrence. At baseline, 680 reported excellent-good cosmesis compared with 42% at 5 years. All patients indicated total satisfaction with overall treatment experience. CONCLUSIONS: APBI using IORT was well tolerated with excellent local control and may be a reasonable alternative to mastectomy for IBTR. Further study is needed to determine the most suitable candidates for this approach.