Yılmaz Tezcan

Geometric dose summation in adjuvant EBRT and VCBT for endometrial cancer: A retrospective dosimetric analysis

In patients with gynecologic malignancies treated with external beam radiotherapy (EBRT) and vaginal cuff brachytherapy (VCBT), accurate dose summation is essential for assessing organ-at-risk (OAR) exposure. This study aimed to compare dosimetric differences between rigid image-based plan summation and conventional linear equivalent dose in 2 Gy fractions (EQD2) summation in adjuvant endometrial cancer radiotherapy. Fourteen patients who received adjuvant EBRT and VCBT following hysterectomy were retrospectively analyzed. VCBT plans were converted to EQD2 (α/β = 10) and combined with EBRT plans using rigid image fusion to create a composite "plan sum." Rectum, bladder, and sigmoid D2cc values were extracted from this summed geometry and compared with D2cc values calculated using the simple-sum method. The "dog-ear" region, representing residual vaginal tissue, was also evaluated. The plan-sum method consistently yielded lower D2cc values for all OARs compared to the simple-sum technique (p = 0.01). Median D2cc values for the rectum, bladder, and sigmoid were 2.12 Gy, 4.06 Gy, and 1.84 Gy lower, respectively. No statistically significant difference was found in mean or minimum dog-ear doses between methods. Rigid image-based plan summation provides more anatomically realistic dose estimates than conventional EQD2 summation. This technique may improve cumulative dose assessment and planning precision in adjuvant VCBT for endometrial cancer, particularly in anatomically stable high-risk regions.

Efficacy of cumulative cisplatin dose on survival in patients with locally advanced cervical cancer treated with definitive chemoradiotherapy: multicenter study by Turkish Oncology Group

To investigate the impact of cumulative cisplatin dose on clinical outcomes in locally advanced cervical cancer patients undergoing definitive chemoradiotherapy. A retrospective analysis was conducted on 654 patients with stage IB3-IVA disease treated with definitive chemoradiotherapy. Radiotherapy was applied as external beam pelvic with or without para-aortic radiotherapy and brachytherapy. Concomitant chemotherapy was in the form of weekly or 3 weekly cisplatin. Data on demographics, treatment protocols, cumulative cisplatin dose, adverse effects, and survival outcomes were collected. Statistical analyses, including univariate and multivariate Cox regression models, were used to assess factors influencing progression free survival and overall survival. The median cumulative cisplatin dose was 210 mg (range 40-320), and ≥200 mg in 503 (76.9%) patients. Median follow-up was 35 months (range 1-150). The 5 year progression free survival and overall survival rates were 66.9% and 77.1%, respectively. Multivariate analysis identified poor performance status, non-squamous cell histology, presence of lymph node metastases, and hemoglobin 200 mg, particularly in patients with lymph node metastases, significantly improved overall survival. Factors such as anemia, toxicity related challenges, and comorbidities were identified as critical considerations in treatment planning. These findings emphasize the balance between maximizing therapeutic efficacy and managing toxicity, guiding personalized treatment approaches for locally advanced cervical cancer.