Harnessing Radiation Technology to Improve Survival
Authors: Andrea Bezjak
Journal: Journal of Clinical Oncology (2011)

Radiotherapy (RT) continues to be an effective treatment of many cancers; it is able to provide improved local control, disease eradication, and valuable symptom palliation in virtually all malignancies. The past decades have witnessed tremendous technological advances in the simulation, planning, and delivery of RT. The tools currently at our disposal allow for more accurate identification of the tumor, sophisticated planning and sculpting of radiation dose, and the ability to correct even minor discrepancies in the patient position on the treatment unit. These tools have improved the geometric accuracy of radiation delivery, which allows us to use tighter margins around the tumor, which in turn can reduce normal tissue exposure and toxicity and permit us to prescribe higher RT dose, thus offering a greater chance for local control. These technological advances have changed and continue to change the practice of radiation oncology for all cancer sites. Lung cancer is a particularly grateful recipient of these advances. One would be hard pressed to find another cancer that subjects its radiation oncology practitioners to the simultaneous challenges of target delineation, identification of full extent of disease, tumor motion, lung tissue heterogeneity effect on radiation dose distribution, and the presence of multiple critical organs with limited ability to tolerate radiation damage—all while reminding practitioners that no two tumors and no two patients are exactly the same. Thus, the technological advances of target identification, planning, assessment and control of motion, and more accurate planning and delivery of image-guided RT are revolutionizing modern lung RT. However, the advances come at a cost, and this is by no means limited to the initial investment of buying the latest tools. The cost also includes the education; the knowledge transfer; the time needed to train practitioners in the proper adoption of technology; and changes in radiation planning, delivery, and quality assurance processes to implement the emerging technologies in the best way to improve the care of patients. The use of the novel technology has resulted in new billing codes that quickly add up; the escalating cost of our health expenditures bears witness to that. Although the cost of RT is but a small proportion of the cost of cancer care, we all have the collective responsibility to advance those technologies that indeed make a difference in the lives of our patients, and we have to ask critically whether all of the technological advances indeed contribute to our ability to cure more patients. It is with such a mind-set that we welcome the article by Chen et al that accompanies this editorial. The authors have analyzed Surveillance, Epidemiology, and End Results (SEER) –Medicare data to identify patients with stage III non–small-cell lung cancer (NSCLC) who were diagnosed between 2000 and 2005 and who received thoracic radiation within 6 months of diagnosis; Chen et al focused on whether or not patients received computed tomography (CT) –based simulation (as an indicator of three-dimensional [3D] treatment planning) and how that may have influenced their outcomes. Of more than 10,000 patients identified with stage III NSCLC, 52% had received thoracic radiation as part of their initial treatment; 60% of those underwent CT-based simulation. Even when controlling for the known clinical and demographic variables, as well as for comorbidity and other treatment received, patients who underwent CT simulation to plan their thoracic radiation had a significant reduction in the risk of death (HR, 0.77; P .1) when compared with those whose thoracic radiation was traditionally planned. It is possible that CT simulation was a marker of higher-dose thoracic radiation, given that actual doses prescribed or delivered were not available. However, patient characteristics that may be associated with lower likelihood of prescribing high-dose radiation (eg, advanced age) were not associated with a different pattern of use of CT simulation; in actual fact, the proportion of patients undergoing CT simulations in ages 65 to 69, 70 to 74, 75 to 79, and 80 and older was virtually identical. Thus, the data does indeed support the hypothesis that more accurate identification of the target and more precise radiation planning, as afforded by CT-based simulation, is associated with improved patient outcomes. 3D treatment planning allows for identification of the dosage delivered to organs at risk and a potential to modify plans to reduce toxicity. In addition, identifying the target more accurately reduces the risk of geographic miss and the need for additional margins for uncertainty. Thus, the benefit increases, and the risk can decrease—a true coup when trying to maximize the therapeutic ratio. The assumption is that 3D treatment planning led to better local control, which in turn resulted in improved survival. Reliable and accurate documentation of local control is extremely challenging; this is one aspect of technological advances that remains insufficiently developed. However, better local control can indeed result in improved survival in lung cancer; one of the best pieces of evidence continues to be the phase III trial of continuous hyperfractionated accelerated RT versus conventional radiation: increasing the radiobiologic potency of radiation through an accelerated hyperfractionated regimen improved survival of patients with NSCLC without the use of chemotherapy (and to a degree virtually identical to the improvement obtained by adding of chemotherapy to radiation in contemporaneous studies). Another interesting piece of data in the article by Chen et al is the variability in the uptake of CT-based simulation for stage III NSCLC that they identified; use of CT-based simulation increased from only 34% in 2000 to 58% in 2002 and to 77.6% in 2005. Diagnostic CT JOURNAL OF CLINICAL ONCOLOGY E D I T O R I A L S VOLUME 29 NUMBER 17 JUNE 1