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Author(s): Beyza Sirin Ozdemir (corresponding author) [1]; Ali A Yavuz [1] Introduction Radiotherapy (RT) is an important component of multimodal therapy in small-cell lung cancer (SCLC). SCLC is highly radiosensitive.[sup.[1]] [...], Background: Tumor shrinkage is frequently observed during conventionally fractionated chemoradiotherapy for limited-stage small-cell lung cancer (SCLC). The specific goals of this study are to evaluate the gross tumor volume (GTV) changes due to treatment-induced tumor reduction during the course of radiotherapy (RT) and to examine its potential use in adaptive radiotherapy (ART) for tumor dose escalation or normal tissue sparing in patients with SCLC. Materials and Methods: A total of 10 patients with SCLC eligible for chemoradiotherapy underwent computed tomography (CT) scan after Fractions 13 and 23 (at nominal doses of 23.4 Gy and 41.4 Gy, respectively). The GTV was delineated on the repeat CT scans, and two treatment plans were generated with or without adaptation to tumor shrinkage during RT for each patient. Dosimetric and volumetric analyses were performed. Results: The average GTV reduction observed over 13 fractions was 58.5 (range: 13.2-92.3; P < 0.001) and over 23 fractions was 70 (range: 36.9-84.5; P < 0.001). Compared with the plan without adaptation, ART resulted in mean lung dose relative decreases of 8.7, mean lung volume receiving ≥20 Gy relative decreases of 5, mean lung volume receiving ≥5Gy relative decreases of 10, mean medulla spinalis dose relative decreases of 21 cGy, mean esophagus volume receiving ≥50 Gy relative decreases of 19, and mean heart volume receiving ≥42 Gy relative decreases of 13. The benefits of ART were the greatest for tumor volumes ≥30 cm[sup.3] and are directly dependent on GTV reduction during treatment. Conclusion: ART for SCLC achieved a significant benefit in terms of organ at risk (OAR) and dose escalation. Keywords: Adaptive radiotherapy, dose-volume histograms, small-cell lung cancer

Purpose. To evaluate the predictive potency of a novel index combining the pan‐immune‐inflammatory index and hemoglobin levels (PIV/Hb) for the prevalence of radiation‐induced trismus (RIT) in patients with locally advanced nasopharyngeal cancer (LA‐NPC) receiving concurrent chemoradiotherapy (CCRT). Methods. Data from 228 LA‐NPC patients were retrospectively examined. Maximum mouth openings (MMO) were measured to confirm the presence of RIT, defined as MMOs ≤35 mm. Complete blood test results from the first day of CCRT were used to calculate PIV/Hb levels. A potential relationship between pretreatment PIV/Hb and the RIT status was evaluated using receiver operating characteristic (ROC) curve analysis. Results. Post‐CCRT RIT was diagnosed in 20.2% of the patients. The ROC curve analysis determined 68.4 g/dL as the ideal PIV/Hb cutoff that effectively divided patients into two distinct groups (area under the curve: 94.7%; specificity: 86.4%; sensitivity: 87.4%). RIT was significantly more prevalent in the PIV/Hb > 68 group than in the PIV/Hb < 68 group (58.8% vs. 3.8%; P < 0.001). Multivariate logistic regression analysis showed that a pre‐CCRT PIV > 68 was independently associated with significantly higher rates of RIT. Conclusion. Higher pretreatment levels of the novel PIV/Hb index predict increased RIT rates following definitive CCRT for LA‐NPCs. [ABSTRACT FROM AUTHOR]

Considering the high rates of long-term survival in breast cancer patients, it is crucial to determine the most appropriate RT technique in order to prevent RT-related heart and lung damage and other complications that may adversely affect quality of life. In this study, we aimed to detect the superior radiotherapy technique in patients with breast cancer in terms of the target volumes and the organ at risk (OAR). We included 20 breast cancer patients who were applied modified radical mastectomy. Two different treatment plans (IMRT and 3DCRT) were prepared for each patient. Chest wall, supraclavicular, axillary and/or mammaria interna lymphatic regions were contoured as clinical target volüme (CTV). For planning target volüme (PTV), 0.5 cm was added to CTV (post margin; 0.3 cm). The doses of the target volumes and the OAR volumes (contralateral breast, heart, ipsilateral lung), the homogeneity index (HI) were compared. For the heart, the contralateral breast, the ipsilateral lung, Dmean and V25, Dmean and Dmax, D5 and D20 were evaluated, respectively. In addition, D2, D98, D95 ve Dmean were investigated for the PTV. Mann Whitney test was used for statistical analysis and p< 0.05 was considered significant. IMRT technique was superior to the 3DCRT in terms of the PTV, the OAR volumes and the HI. However, irradiated contralateral breast volume was less in the 3DCRT technique. [ABSTRACT FROM AUTHOR]