Three-dimensional conformal radiotherapy in bronchogenic carcinoma: considerations for implementation

Apigenin induces apoptosis in human lung cancer H460 cells through caspase- and mitochondria-dependent pathways

Apigenin (4,5,7-trihydroxyflavone), a promising chemopreventive agent presented in fruits and vegetables, has been shown to induce cell cycle arrest and apoptosis in many types of human cancer cell lines. However, there is no available information to address the effects of apigenin on human lung cancer H460 cells. In the present studies, H460 cells were treated with apigenin for different time and then were analyzed for the morphological changes, induction of apoptosis, protein levels associated with apoptosis and results in dose-dependent induction of morphological changes, decrease in the percentage of viability, induced DNA damage and apoptosis; down-modulation of the protein expression of Bid, Bcl-2, procaspase-8; up-regulation of protein levels of Bax, caspase-3, AIF, cytochrome c, GRP78 and GADD153; decreased the levels of mitochondrial membrane potential and increased the productions of reactive oxygen species (ROS) and Ca2+ in H460 cells. Taken together, this is the first systematic in vitro study showing the involvement of apoptosis regulatory proteins as potential molecular targets of apigenin in human lung cancer H460 cells.

Radiotherapy Planning Complexity and Survival after Treatment of Advanced Stage Lung Cancer in the Elderly

PURPOSE: Complex radiotherapy (RT) planning is increasingly common in the treatment of lung cancer though it remains unclear if these treatments are associated with better outcomes. We evaluated the association between the complexity of RT planning simulation with survival among elderly Stage IIIB non-small cell lung cancer (NSCLC) patients. METHODS: We included all patients aged >65 years with histologically confirmed Stage IIIB NSCLC diagnosed between 1992 and 2002 receiving chemotherapy and RT from the Surveillance, Epidemiology, and End Results registry linked to Medicare claims. Patients were divided into simple, intermediate, and complex RT planning groups using Medicare physician codes. Kaplan-Meier curves and Cox regression were used to compare overall and lung cancer-specific survival rates across groups. RESULTS: We identified 1,733 patients: 148 (8%), 1,138 (66%), and 447 (26%) were classified as having received simple, intermediate and complex RT planning, respectively. Baseline characteristics were similar across groups. Increasing complexity of RT planning was significantly associated with better overall survival (p=0.0002). Multivariate analyses showed that intermediate (HR: 0.75, 95% CI: 0.62 to 0.91) and complex planning (HR: 0.69, 95% CI: 0.55 to 0.86) were associated with better overall survival compared to simple RT planning. Similar results were observed for lung cancer-specific survival analyses. Toxicities were comparable across groups. CONCLUSIONS: The use of more complex RT planning and simulation methods is associated with better survival in elderly patients with Stage IIIB NSCLC. Although these results should be further validated in prospective clinical trials, this data suggests that complex planning may improve the outcomes of these patients.

Digital fluoroscopy to quantify lung tumor motion: potential for patient-specific planning target volumes

PURPOSE

To apply digital fluoroscopy integrated with CT simulation to measure lung tumor motion and aid in the quantification of individualized planning target volumes.

METHODS AND MATERIALS

A flat panel digital fluoroscopy unit was modified and integrated with a CT simulator. The stored fluoroscopy images were overlaid with digitally reconstructed radiographs, allowing measurement of the observed lung tumor motion in relation to the corresponding contours on the static digitally reconstructed radiographs. CT simulation and digital fluoroscopy was performed on 10 patients with non-small-cell lung cancer. Actual tumor motion was measured in three dimensions using the overlaid images.

RESULTS

Combining the dynamic data with digitally reconstructed radiographs allowed the tumor shadow from the fluoroscopy to be tracked in relation to the CT lung tumor contour. For all patients, the extent of tumor motion in three dimensions was unique. The motion was greatest in the superoinferior direction and minimal in the AP and lateral directions.

CONCLUSION

We have developed a tool that allows CT simulation to be combined with digital fluoroscopy. Quantitative evaluation of the tumor motion in relation to the CT plan allows for customization of the planning target volume. The variability observed clearly demonstrates the need to generate patient-specific internal motion margins.

Integration of digital fluoroscopy with CT-based radiation therapy planning of lung tumors

Radiation dose escalation may be a means to increase the local control rate of inoperable lung tumors. Treatment plans involve the creation of a uniform planning target volume (PTV) to ensure proper coverage despite patient breathing and setup error. This may lead to unnecessary radiation of normal tissue in shallow breathers or target underdosing for patients with excess internal motion. Therefore, the nature of tumor motion for each patient should be measured in 3D, something that cannot be done with CT alone. We have developed a method that acquires 2D real-time fluoroscopic images (loops) and coregisters them with 2D digitally reconstructed radiographs (DRR) formed from the CT scan. The limitations of CT to encompass motion can be overcome by merging the two modalities together. The accuracy of the coregistration method is tested with a stationary grid of radio-opaque markers at various spatial positions. The in-plane (at-depth) displacement between markers on the fluoroscopic image versus the DRR varies with position across the image due to slight misalignments between the x-ray source used in fluoroscopy and the virtual source used for the DRR relative to the test object. At clinically relevant positions, the maximum, measured in-plane displacement, is 1.1 mm. The method is applied to the thorax of an anthropomorphic phantom and a good fit is observed between the appearances of the bony anatomical structures on the coregistered image. Finally, a series of motion measurements are carried out on two oscillating cylindrical objects. The degree of motion as measured by fluoroscopy is accurate to within 1.0 mm, whereas the DRR is inconsistent in predicting motion. The coregistration of fluoroscopic loops with the DRR shows at what point within the oscillation the DRR fails to encompass motion. For any treatment site involving target motion, this real-time imaging is a useful asset in the planning stage.

The rationale and use of three-dimensional radiation treatment planning for lung cancer

Treatment of lung cancer with conventional radiation therapy is associated with suboptimal local tumor control and poor long-term survival. Poor local tumor control may result from inaccurate tumor targeting, failure to satisfactorily conform to dose distribution with the target volume, and/or inadequate radiation doses. Three-dimensional treatment planning is a radiotherapy technique that provides more accurate dose targeting via the direct transfer of three-dimensional anatomic information from diagnostic scans into the planning process. This technology can assist treatment planning by providing dose-volume histograms, an estimation of normal tissue complication probabilities, and facilitate dose escalation. Preliminary clinical studies suggest that this is a feasible approach worthy of additional study. The three-dimensional tools provide new opportunities to better understand radiation-induced changes in pulmonary function.