Evaluation of skin dose associated with different frequencies of bolus applications in post-mastectomy three-dimensional conformal radiotherapy

<p>Abstract</p> <p>Background</p> <p>The study aimed to calculate chest-wall skin dose associated with different frequencies of bolus applications in post-mastectomy three-dimensional conformal radiotherapy (3D-CRT) and to provide detailed information in the selection of an appropriate bolus regimen in this clinical setting.</p> <p>Methods</p> <p>CT-Simulation scans of 22 post-mastectomy patients were used. Chest wall for clinical target volume (CTV) and a volume including 2-mm surface thickness of the chest wall for skin structures were delineated. Precise PLAN 2.11 treatment planning system (TPS) was used for 3D-CRT planning. 50 Gy in 25 fractions were prescribed using tangential fields and 6-MV photons. Six different frequencies of bolus applications (0, 5, 10, 15, 20, and 25) were administered. Cumulative dose-volume histograms were generated for each bolus regimen. The minimum, maximum and mean skin doses associated with the bolus regimens were compared. To test the accuracy of TPS dose calculations, experimental measurements were performed using EBT gafchromic films.</p> <p>Results</p> <p>The mean, minimum and maximum skin doses were significantly increased with increasing days of bolus applications (p < 0.001). The minimum skin doses for 0, 5, 10, 15, 20, and 25 days of bolus applications were 73.0% ± 2.0%, 78.2% ± 2.0%, 83.3% ± 1.7%, 88.3% ± 1.6%, 92.2% ± 1.7%, and 93.8% ± 1.8%, respectively. The minimum skin dose increments between 20 and 25 (1.6% ± 1.0%), and 15 and 20 (4.0% ± 1.0%) days of bolus applications were significantly lower than the dose increments between 0 and 5 (5.2% ± 0.6%), 5 and 10 (5.1% ± 0.8%), and 10 and 15 (4.9% ± 0.8%) days of bolus applications (p < 0.001). The maximum skin doses for 0, 5, 10, 15, 20, and 25 days of bolus applications were 110.1% ± 1.1%, 110.3% ± 1.1%, 110.5% ± 1.2%, 110.8% ± 1.3%, 111.2% ± 1.5%, and 112.2% ± 1.7%, respectively. The maximum skin dose increments between 20 and 25 (1.0% ± 0.6%), and 15 and 20 (0.4% ± 0.3%) days of bolus applications were significantly higher than the dose increments between 0 and 5 (0.2% ± 0.2%), 5 and 10 (0.2% ± 0.2%), and 10 and 15 (0.2% ± 0.2%) days of bolus applications (p ≤ 0.003). The TPS overestimated the near-surface dose 10.8% at 2-mm below the skin surface.</p> <p>Conclusion</p> <p>In post-mastectomy 3D-CRT, using a 1-cm thick bolus in up to 15 of the total 25 fractions increased minimum skin doses with a tolerable increase in maximum doses.</p

The percentage of ALK-positive cells and the efficacy of first-line alectinib in advanced non-small cell lung cancer: is it a novel factor for stratification? (Turkish Oncology Group Study)

Introduction Alectinib is an effective second-generation ALK tyrosine kinase inhibitor (TKI) used in the first-line treatment of patients with advanced ALK-positive NSCLC. Recent studies demonstrated that the percentage of ALK-positive tumor cells in patient groups receiving crizotinib might affect outcomes. This study aimed to investigate whether the percentage of ALK-positive cells had a predictive effect in patients with advanced NSCLC who received first-line Alectinib as ALK-TKI. Materials and methods This retrospective study included patients with advanced-stage NSCLC who received alectinib as a first-line ALK-TKI and whose percentage of ALK-positive cells was determined by FISH at 27 different centers. Patients who received any ALK-TKI before alectinib were not included in the study. Patients were separated into two groups according to the median (40%) value of the percentage of ALK-positive cells (high-positive group >= 40% and low-positive group = 60%, the median PFS was 4.5, 17.1, and 26 months, respectively, and could not be reached in the >= 60% group. Conclusion Our study demonstrated that the efficacy of alectinib varies significantly across patient subgroups with different percentages of ALK-positive cells. If these findings are prospectively validated, the percentage of ALK-positive cells may be used as a stratification factor in randomized trials comparing different ALK-TKIs

The safety and efficacy of first-line atezolizumab plus bevacizumab in patients with unresectable hepatocellular carcinoma: A multicenter real-world study from Turkey

The aim of the study was to evaluate the real-world clinical outcomes of atezolizumab and bevacizumab (Atez/Bev) as the initial therapy for advanced hepatocellular carcinoma (HCC). We retrospectively analyzed 65 patients treated with Atez/Bev for advanced HCC from 22 institutions in Turkey between September 2020 and March 2023. Responses were evaluated by RECIST v1.1 criteria. The median progression-free survival (PFS) and overall survival (OS) were calculated using the Kaplan-Meier method. Cox regression model was employed to conduct multivariate analyses. The median age was 65 (range, 22-89) years, and 83.1% of the patients were male. A total of 1.5% achieved a complete response, 35.4% had a partial response, 36.9% had stable disease, and 26.2% had progressive disease. The disease control rate was 73.8% and associated with alpha-fetoprotein levels at diagnosis and concomitant antibiotic use. The incidence rates of any grade and grade ≥ 3 adverse events were 29.2% and 10.7%, respectively. At a median follow-up of 11.3 (3.4-33.3) months, the median PFS and OS were 5.1 (95% CI: 3-7.3) and 18.1 (95% CI: 6.2-29.9) months, respectively. In univariate analyses, ECOG-PS ≥ 1 (relative to 0), Child-Pugh class B (relative to A), neutrophil-to-lymphocyte ratio (NLR) > 2.9 (relative to ≤ 2.9), and concomitant antibiotic use significantly increased the overall risk of mortality. Multivariate analysis revealed that ECOG-PS ≥ 1 (HR: 2.69, P = .02), NLR > 2.9 (HR: 2.94, P = .017), and concomitant antibiotic use (HR: 4.18, P = .003) were independent predictors of OS. Atez/Bev is an effective and safe first-line therapy for advanced-stage HCC in a real-world setting. The survival benefit was especially promising in patients with a ECOG-PS score of 0, Child-Pugh class A, lower NLR, and patients who were not exposed to antibiotics during the treatment