A dosimetric comparison of double-arc volumetric arc therapy, step-shoot intensity modulated radiotherapy and 3D-CRT for left-sided breast cancer radiotherapy after breast-conserving surgery.

OBJECTIVE: To compare the dosimetric and efficiency differences for left-sided breast cancer radiotherapy after breast-conserving surgery among three different planning techniques: double-arc volumetric-modulate arc therapy (VMAT), step-shoot intensity-modulated radiotherapy (sIMRT) and three-dimensional conformal radiation therapy (3D-CRT). MATERIALS AND METHODS: A total of 17 female patients with left-sided breast cancer who underwent breast-conserving surgery were selected; the prescription doses were 50 Gy in 25 fractions. For every patient VMAT, sIMRT and 3D-CRT plans were generated within the Monaco treatment planning system for an Axesse™ accelerator equipped with the Agility MLC. The Conformity Index (CI), the Homogeneity Index (HI), the dose volume histogram (DVH) parameters for the organs at risk and the delivery efficiency were evaluated. RESULTS: The VMAT plans showed on average higher CI of PTV (0.77 ± 0.03) than both sIMRT (0.68 ± 0.02) and 3D-CRT (0.55 ± 0.04) plans (P< 0.05). The HI values in the VMAT, sIMRT and 3D-CRT plans were 0.10 ± 0.01 0.09 ± 0.01 and 0.13 ± 0.01 (P> 0.05), respectively, and the differences among the three techniques were not statistically significant. In the ipsilateral lung, the VMAT plans showed lower Dmean, V30, V20, and V10 than the sIMRT and 3D-CRT (P< 0.05); however, there was no significant difference in V5. In the heart, the VMAT plans had lower V30 and V20 than the sIMRT and 3D-CRT plans (P< 0.05), but there was no significant difference in the Dmean and V5. In the contralateral lung, the VMAT plans showed higher Dmean and V5 than sIMRT and 3D-CRT (P< 0.05). In the contralateral breast, the VMAT plans had a higher V5 than the sIMRT and 3D-CRT plans (P< 0.05). The VMAT plans had higher MU's than sIMRT and 3D-CRT, while the treatment times were lower than that of sIMRT. CONCLUSION: For left-sided breast cancer radiotherapy after breast-conserving surgery, the VMAT plans had a better CI than the sIMRT and 3D-CRT plans. The VMAT and the sIMRT plans had better HI than the 3D-CRT plans, but no significant difference was observed between VMAT and sIMRT.

Analysis of the correlation between P53 and Cox-2 expression and prognosis in esophageal cancer.

The present study aimed to explore the importance of P53 and Cox-2 protein expression in esophageal cancer and assess their influence on prognosis. The expression of P53 and Cox-2 was assessed in esophageal cancer samples from 195 patients subjected to radical surgery at Changzhou First People's Hospital (Changzhou, China) between May 2010 and December 2011. Expression of P53 and Cox-2 proteins were detected in 60.5% (118/195) and 69.7% (136/195) of the samples, respectively, and were co-expressed in 43.1% (84/195) of the samples. A correlation was identified between P53 expression and overall survival (OS) (P=0.0351) as well as disease-free survival (DFS) (P=0.0307). In addition, the co-expression of P53 and Cox-2 also correlated with OS (P=0.0040) and DFS (P=0.0042). P53 expression (P=0.023), TNM staging (P<0.001) and P53/Cox-2 co-expression (P=0.009) were identified as independent factors affecting OS in patients with esophageal cancer via a Cox multivariate regression model analysis. A similar analysis also identified P53 expression (P=0.020), TNM staging (P<0.001) and P53/Cox-2 co-expression (P=0.008) as independent prognostic factors influencing DFS in these patients. Binary logistic regression analysis demonstrated a correlation between P53 expression (P=0.012), TNM staging (P<0.001), tumor differentiation level (P=0.023) and P53/Cox-2 co-expression (P=0.021), and local recurrence or distant esophageal cancer metastasis. The results of the present study indicate that P53 and Cox-2 proteins may act synergistically in the development of esophageal cancer, and the assessment of P53/Cox-2 co-expression status in esophageal cancer biopsies may become an important diagnostic criterion to evaluate the prognosis of patients with esophageal cancer.

The status of perineural invasion predicts the outcomes of postoperative radiotherapy in locally advanced esophageal squamous cell carcinoma.

BACKGROUND: Prognosis of locally advanced esophageal squamous cell carcinoma (ESCC) remains dismal even after curative resection and adjuvant radiotherapy. New biomarkers for predicting prognosis and treatment outcomes are needed for improved treatment stratification of patients with locally advanced ESCC. The prognostic and treatment predictive significance of perineural invasion (PNI) in the locally advanced ESCC remains unclear. This study aimed to examine the effect of PNI on the outcomes of locally advanced ESCC patients after curative resection with or without postoperative radiotherapy (PORT). PATIENTS AND METHODS: We retrospectively reviewed 262 consecutive locally advanced ESCC patients who underwent curative resection. Tumors sections were re-evaluated for PNI by an independent pathologist blinded to the patients' outcomes. Overall survival (OS) and disease-free survival (DFS) were determined using the Kaplan-Meier method; univariate log-rank test and multivariate Cox proportional hazard model were used to evaluate the prognostic value of PNI. RESULTS: Finally, 243 patients were analyzed and enrolled into this study, of which 132 received PORT. PNI was identified in 22.2% (54/243) of the pathologic sections. The 5-year DFS was favorable for PNI-negative patients versus PNI-positive patients (21.3% vs. 36.7%, respectively; P = 0.005). The 5-year OS was 40.3% for PNI-negative patients versus 21.7% for PNI-positive patients (P < 0.001). On multivariate analysis, PNI was an independent prognostic factor. In a subset analysis for patients received PORT, PNI was evaluated as a prognostic predictor as well (P < 0.05). In contrast to patients without PORT, PORT couldn't improve the disease recurrence and survival in locally advanced ESCC patients with PNI-positive (P > 0.05). CONCLUSIONS: PNI could serve as an independent prognostic factor and prognosticate treatment outcomes in locally advanced ESCC patients. The PNI status should be considered when stratifying high-risk locally advanced ESCC patients for adjuvant radiotherapy. Future prospective study is warranted to confirm our results.

Proposed Modification of Nodal Staging as an Alternative to the Seventh Edition of the American Joint Committee on Cancer Tumor-Node-Metastasis Staging System Improves the Prognostic Prediction in the Resected Esophageal Squamous-Cell Carcinoma.

INTRODUCTION: The 7th American Joint Committee on Cancer (AJCC) tumor-node-metastasis staging system for esophageal cancer defined N classification based on the number of metastatic lymph nodes (LNs). However, this classification might neglect the extent of LNs metastasis. This study aimed to revise N classification based on the extent of LNs metastasis and propose a modification to the current AJCC staging system for better representing the prognostic characteristics of Chinese esophageal squamous-cell carcinoma (ESCC). METHODS: We retrospectively reviewed 1993 ESCC patients who underwent curative resection. The proposed N categories based on the number of LNs metastasis stations were compared with the current staging system by univariate and multivariate Cox regression analyses. Homogeneity, discriminatory ability, and monotonicity of gradients of two staging systems were compared using likelihood ratio χ statistics and Akaike information criterion calculations. RESULTS: The survival differences were not significant for N2 versus N3 category (p = 0.231) and stages IIIB versus IIIC (p = 0.713) based on the 7th AJCC staging system. When the modified staging system was adopted, the survival difference for N2 versus N3 and IIIB versus IIIC could be well discriminated. Statistical analysis showed that the modified staging system had higher likelihood ratio χ scores and smaller Akaike information criterion values than the 7th AJCC staging system, which represented the optimum prognostic stratification. CONCLUSIONS: The modified staging system with the revised N categories based on the number of LNs metastasis stations better predicts the survival of Chinese ESCC population than the 7th AJCC staging system. Further studies are required to confirm this result.

Single arc volumetric-modulated arc therapy is sufficient for nasopharyngeal carcinoma: a dosimetric comparison with dual arc VMAT and dynamic MLC and step-and-shoot intensity-modulated radiotherapy.

BACKGROUND: The performance of single arc VMAT (VMAT1) for nasopharyngeal carcinoma (NPC) on the Axesse linac has not been well described in previous studies. The purpose of this study is to assess the feasibility of VMAT1 for NPC by comparing the dosimetry, delivery efficiency, and accuracy with dual arc VMAT (VMAT2), dynamic MLC intensity-modulated radiotherapy (dIMRT), and step-and-shoot intensity-modulated radiotherapy (ssIMRT). METHODS: Twenty consecutive patients with non-metastatic NPC were selected to be planned with VMAT1, VMAT2, dIMRT and ssIMRT using Monaco 3.2 TPS on the Axesse™ linear accelerator. Three planning target volumes (PTVs), contoured as high risk, moderate risk and low risk regions, were set to receive median absorbed-dose (D50%) of 72.6 Gy, 63.6 Gy and 54 Gy, respectively. The Homogeneity Index (HI), Conformity Index (CI), Dose Volume Histograms (DVHs), delivery efficiency and accuracy were all evaluated. RESULTS: Mean HI of PTV72.6 is better with VMAT1(0.07) and VMAT2(0.07) than dIMRT(0.09) and ssIMRT(0.09). Mean HI of PTV63.6 is better with VMAT1(0.21) and VMAT2(0.21) than dIMRT and ssIMRT. Mean CI of PTV72.6 is also better with VMAT1(0.57) and VMAT2(0.57) than dIMRT(0.49) and ssIMRT(0.5). Mean CI of PTV63.6 is better with VMAT1(0.76) and VMAT2(0.76) than dIMRT(0.73) and ssIMRT(0.73). VMAT had significantly improved homogeneity and conformity compared with IMRT. There was no significant difference between VMAT1 and VMAT2 in PTV coverage. Dose to normal tissues was acceptable for all four plan groups. VMAT1 and VMAT2 showed no significant difference in normal tissue sparring, whereas the mean dose of the parotid gland of dIMRT was significantly reduced compared to VMAT1 and VMAT2. The mean delivery time for VMAT1, VMAT2, dIMRT and ssIMRT was 2.7 min, 3.9 min, 5.7 min and 14.1 min, respectively. VMAT1 reduced the average delivery time by 29.8%, 51.1% and 80.8% compared with VMAT2, dIMRT and ssIMRT, respectively. VMAT and IMRT could all be delivered accurately based on our quality assurance standards. CONCLUSIONS: In the treatment of NPC using the Axesse™ linear accelerator, single arc VMAT has shown superiority to double arc VMAT, dIMRT and ssIMRT in delivery efficiency, without compromise to the PTV coverage. However, there is still room for improvement in terms of OAR sparing.