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Purpose This study aimed to evaluate the role of postmastectomy radiation therapy (PMRT) in patients with node-negative breast cancer of 5cm or larger tumors undergoing mastectomy. Materials and Methods Medical records of 274 patients from 18 institutions treated with mastectomy between January 2000 and December 2016 were retrospectively reviewed. Among these, 202 patients underwent PMRT, while 72 did not. Two hundred and forty-one patients (88.0%) received systemic chemotherapy, and 172 (62.8%) received hormonal therapy. Patients receiving PMRT were younger, more likely to have progesterone receptor-positive tumors, and received adjuvant chemotherapy more frequently compared with those without PMRT (p < 0.001, p=0.018, and p < 0.001, respectively). Other characteristics were not significantly different between the two groups. Results With a median follow-up of 95 months (range, 1 to 249 months), there were nine locoregional recurrences, and 20 distant metastases. The 8-year locoregional recurrence-free survival rates were 98.0% with PMRT and 91.3% without PMRT (p=0.133), and the 8-year disease-free survival (DFS) rates were 91.8% with PMRT and 73.9% without PMRT (p=0.008). On multivariate analysis incorporating age, histologic grade, lymphovascular invasion, hormonal therapy, chemotherapy, and PMRT, the absence of lymphovascular invasion and the receipt of PMRT were associated with improved DFS (p=0.025 and p=0.009, respectively). Conclusion Locoregional recurrence rate was very low in node-negative breast cancer of 5 cm or larger tumors treated with mastectomy regardless of the receipt of PMRT. However, PMRT was significantly associated with improved DFS. Further investigation is needed to confirm these findings. [ABSTRACT FROM AUTHOR]

Purpose This study aimed to investigate the impact of postoperative radiotherapy (PORT) in de novo metastatic breast cancer (dnMBC) patients undergoing planned primary tumor resection (PTR) and to identify the subgroup of patients who would most benefit from PORT. Materials and Methods This study enrolled 426 patients with dnMBC administered PTR alone or with PORT. The primary and secondary outcomes were overall and progression-free survival (OS and PFS), respectively. Results The median follow-up time was 53.7 months (range, 3.1 to 194.4). The 5-year OS and PFS rates were 73.2% and 32.0%, respectively. For OS, clinical T3/4 category, triple-negative breast cancer (TNBC), postoperative chemotherapy alone were significantly poor prognostic factors, and administration of PORT failed to show its significance. Regarding PFS, PORT was a favorable prognostic factor (hazard ratio, 0.64; 95% confidence interval, 0.50 to 0.82; p < 0.001), in addition to T1/2 category, ≤ 5 metastases, and non-TNBC. According to the multivariate analyses of OS in the PORT group, we divided the patients into three groups (group 1, T1/2 and non-TNBC [n=193]; group 2, T3/4 and non-TNBC [n=171]; and group 3, TNBC [n=49]), and evaluated the effect of PORT. Although PORT had no significance for OS in all subgroups, it was a significant factor for good prognosis regarding PFS in groups 1 and 2, not in group 3. Conclusion PORT was associated with a significantly better PFS in patients with dnMBC who underwent PTR. Patients with clinical T1/2 category and non-TNBC benefited most from PORT, while those with TNBC showed little benefit. [ABSTRACT FROM AUTHOR]

Purpose: We evaluated the role of adjuvant therapy in stage IIIA endometrioid adenocarcinoma patients who underwent surgery followed by radiotherapy (RT) alone or chemoradiotherapy (CTRT) according to risk group. Materials and Methods: A multicenter retrospective study was conducted including patients with surgical stage IIIA endometrial cancer treated by radical surgery and adjuvant RT or CTRT. Disease-free survival (DFS) and overall survival (OS) were analyzed. Results: Ninety-three patients with stage IIIA disease were identified. Nineteen patients (20.4%) experienced recurrence, mostly distant metastasis (17.2%). Combined CTRT did not affect DFS (74.1% vs. 82.4%, p=0.130) or OS (96.3% vs. 91.9%, p=0.262) in stage IIIA disease compared with RT alone. Patients with age ≥ 60 years, grade G2/3, and lymphovascular space involvement had a significantly worse DFS and those variables were defined as risk factors. The high-risk group showed a significant reduction in 5-year DFS (≥ 2 risk factors) (49.0% vs. 88.0%, p < 0.001) compared with the low-risk group (< 2). Multivariate analysis confirmed that more than one risk factor was the only predictor of worse DFS (hazard ratio, 5.45; 95% confidence interval, 2.12 to 13.98; p < 0.001). Of patients with no risk factors, a subset treated with RT alone showed an excellent 5-year DFS and OS (93.8% and 100%, respectively). Conclusion: We identified a low-risk subset of stage IIIA endometrioid adenocarcinoma patients who might be reasonable candidates for adjuvant RT alone. Further randomized studies are needed to determine which subset might benefit from combined CTRT. [ABSTRACT FROM AUTHOR]