Purpose: This study aimed to evaluate the feasibility, dosimetric characteristics, and early clinical outcomes of CyberKnife (CK)-based accelerated partial breast irradiation (APBI) using non-invasive skin fiducial marker tracking in an Asian population. Materials and Methods: We retrospectively analyzed 74 female patients diagnosed with early-stage breast cancer who underwent APBI using the CK system between May 2019 and December 2024. Patient selection was based on the modified 2017 American Society for Radiation Oncology (ASTRO) consensus criteria. The total tumor doses were 30 Gy in 5 consecutive daily fractions. Non-invasive skin fiducial markers were used for respiratory motion tracking. Dosimetric parameters were recorded according to European Society for Radiotherapy and Oncology (ESTRO) and Quantitative Analyses of Normal Tissue Effects in the Clinic (QUANTEC) recommendations. Primary clinical outcomes, acute and chronic toxicities were evaluated during a median follow-up period of 26.5 months. Predictive factors for toxicity were assessed using receiver operating characteristic (ROC) curve analysis. Results: A total of 74 patients having a median age of 56 years were included in the study, with a median follow-up period of 26.5 months. Non-invasive skin fiducial markers demonstrated a strong correlation with internal surgical clips, validating their accuracy for motion tracking. The median conformity and homogeneity indexes were 1.15 and 1.20, respectively. Median mean heart doses were 1 Gy (left-sided) and 0.5 Gy (right-sided), while the ipsilateral lung mean dose was 2.34 Gy. Two patients (2.7%) developed ipsilateral breast tumor recurrence. There were no grade ≥ 2 toxicities or cardiopulmonary events observed. Radiation dermatitis represented the most common acute toxicity (48.6%), whereas breast fibrosis was the most frequent late toxicity (12.2%). Skin D0.03cc > 29.45 Gy and PTV-to-breast volume ratio > 14.5% were associated with grade 1 dermatitis, while a breast volume < 455.2 cm³ and PTV-to-breast volume ratio > 28.9% were predictive of breast fibrosis. Conclusion: By retrospective reviewing, APBI using the CyberKnife system with non-invasive skin fiducial marker tracking is a safe, precise, and effective treatment option for early-stage breast cancer. Although this retrospective study with limited follow-up demonstrated favorable dosimetric outcomes and minimal acute toxicity, further prospective studies with larger cohorts and longer observation are needed to validate these findings.

Purpose: The purpose of the present study is to determine the impact on survival using adjuvant chemotherapy on patients with locally advanced esophageal cancer. Materials and Methods: From 2007 to 2016, we enrolled 127 locally advanced esophageal squamous cell carcinoma patients treated with combined neoadjuvant chemoradiotherapy (nCRT) and surgery. For patients with the pathological residual primary disease (pT+) and/or residual node disease (pN+) after nCRT, adjuvant chemotherapy was also given after consideration of the toxicity of nCRT, patient performance, and/or comorbidity. The regimen of adjuvant chemotherapy was cisplatin 20 mg/m²/day and 5-fluorouracil 800 mg/m²/day on days 1 through 4 and 22 through 25. The primary endpoint was overall survival (OS). Results: From a total of 127 patients, 26 of them (20.5%) received adjuvant chemotherapy. In the multivariate analysis, pN+ diseases were independently associated with poor OS (hazard ratio (HR): 4.117, 95% confidence interval (CI): 1.366–12.404; p = 0.012). For those with pN+ diseases, their 5-year OS was 36.4% in the follow-up arm compared with 45.8% in the adjuvant chemotherapy arm (p = 0.094). Conclusions: Pathologic node-positive disease is associated with poor OS in locally advanced esophagus cancer patients after combined treatments with nCRT and surgery. Adjuvant chemotherapy appeared to have improved OS in pathologic node-positive diseases.