Prognostic significance of lung radiation dose in patients with esophageal cancer treated with neoadjuvant chemoradiotherapy.

BACKGROUND: The prognostic significance of radiation dose to the lung or heart is unknown in esophageal cancer patients receiving neoadjuvant chemoradiotherapy followed by surgery (trimodal therapy). This study aimed to determine the association between lung and heart radiation dose volumes and prognosis of esophageal cancer after trimodal therapy. METHODS: This study reviewed 123 esophageal cancer patients treated with trimodal therapy in two tertiary institutions between 2010 and 2015. The dose-volume histogram parameter of Vx was defined as the percentage of total organ volume receiving a radiation dose of x (Gy) or more. Predictors of overall survival (OS) were identified using Cox regression models. Receiver-operating characteristic curves were used to select cut-off values for dose-volume. RESULTS: Median follow-up was 28.3 months (range: 4.7-92.8 months). Median OS and progression-free survival were 34.0 months (95% confidence interval [CI]: 27.4-40.6 months) and 24.8 months (95% CI, 18.9-30.7 months), respectively. Multivariate analyses showed that lung V20 (hazard ratio, 1.09; 95% CI: 1.04-1.14; p < 0.001) and lung V5 (hazard ratio, 1.02; 95% CI: 1.00-1.05; p = 0.03) were associated with OS when adjusting for surgical margin and pathological treatment response. The 5-year OS for patients with lung V20 ≤ 23% vs. patients with lung V20 > 23% was 54.4% vs. 5% (p < 0.001) whereas that for patients with lung V5 ≤ 56% vs. patients with lung V5 > 56% was 81.5% vs. 23.4% (p < 0.001). Mean heart dose showed no association with survival outcomes. CONCLUSIONS: Lung radiation dose was independently associated with survival outcomes in esophageal cancer patients treated with neoadjuvant chemoradiotherapy and surgery.

Development of delineation for the left anterior descending coronary artery region in left breast cancer radiotherapy: An optimized organ at risk.

BACKGROUND AND PURPOSE: The left anterior descending coronary artery (LAD) and diagonal branches (DBs) are blurred on computed tomography (CT). We aimed to define the LAD region (LADR) with adequate inclusion of the LAD and DBs and contouring consistency. METHODS AND MATERIALS: The LADR was defined using coronary CT angiograms. The inclusion ratio was used to assess the LAD and DBs inclusion by the LADR. Four radiation oncologists delineated the LAD and LADR, using contrast-enhanced CT of 15 patients undergoing left breast radiotherapy. The Sørensen-Dice similarity index (DSI), Jaccard similarity index (JSI), and Hausdorff distance (HD) were calculated to assess similarity. The mean dose (Dmean) and maximum dose (Dmax) to the LAD and LADR were calculated to compare consistency. Correlations were evaluated using Pearson's correlation coefficient. RESULTS: The inclusion ratio of the LAD by the LADR was 96%. The mean DSI, JSI, and HD values were respectively 27.9%, 16.7%, and 0.42mm for the LAD, and 83.1%, 73.0%, and 0.18mm for the LADR. The Dmean between the LAD and LADR were strongly correlated (r=0.93). CONCLUSION: Delineation of the LADR significantly improved contouring similarity and consistency for dose reporting. This could optimize dose estimation for breast radiotherapy.

Dosimetric predictors of acute haematological toxicity in oesophageal cancer patients treated with neoadjuvant chemoradiotherapy.

OBJECTIVE: Haematological toxicity (HT) is common in patients with oesophageal cancer (EC) treated with chemoradiotherapy (CRT). The Quantitative Analysis of Normal Tissue Effects in the Clinic guidelines provide no dose constraints for the bone marrow (BM) to avoid HT. We aimed to determine dosimetric factors associated with HT during CRT for EC. METHODS: 41 patients with EC treated with neoadjuvant cisplatin and 5-fluorouracil-based CRT were retrospectively reviewed. Associations between the dose-volume histogram parameters of thoracic bones and blood cell count changes during CRT were assessed using logistic regression analyses. Receiver-operating characteristic curves were used to derive optimal dosimetric planning constraints. Vx indicates the total organ volume percentage exceeding a radiation dose of x (Gy). RESULTS: Greater thoracic vertebrae and rib irradiation doses, including mean vertebral dose (MVD), thoracic vertebrae V5-30 (TVV5-30), mean rib dose and rib V5-20, were associated with increased leukopenia (grade ≥ 3) risk. Additional BM sites (sternum, scapulae and clavicles) did not influence HT. White blood cell and absolute neutrophil count nadirs were associated with increased irradiation doses to the thoracic vertebrae, ribs and sternum. Chemotherapy cycle number was not significantly associated with severe neutropenia or leukopenia. Cut-off values with the highest likelihood of avoiding leukopenia were MVD < 25.9 Gy, TVV20 < 70% and TVV10 < 77%. CONCLUSION: Thoracic bone irradiation dose was significantly associated with HT after adjusting for chemotherapy effects. Efforts to maintain MVD < 25.9 Gy, TVV10 < 77% and TVV20 < 70% could reduce HT. ADVANCES IN KNOWLEDGE: This is the first study addressing issues concerning HT in patients with neoadjuvant CRT-treated EC.