Oligometastatic disease (OMD) is a clinical evolution of cancer in which it has spread beyond the primary site but is not yet broadly metastatic. Oligometastases in radiation oncology are typically defined as being 1 to 5 metastatic lesions that can be safely treated with or without a controlled primary tumor. While multiple factors, including individual's overall health, tumor characteristics and treatment goals, play a crucial role in determining the most appropriate multidisciplinary approach to treating OMD, stereotactic body radiation therapy (SBRT) remains a cornerstone in the standard of care for local OMD therapy and data from multiple clinical trials conducted over several years proved its efficacy in the treatment of oligometastases.
However, traditional SBRT plan generation is a time-consuming process that involves thorough effort. A plan can take up to 5 to 10 working days to be generated in addition to CT-simulation as well as multiple clinical and treatment visits. As the time factor is essential in radiation oncology (RO), extended time to delivery can be a strain for people with OMD. This is particularly challenging in OMD due to the multiple disease sites for treatment (up to 5 in a course) as well as the need to coordinate care with ongoing systemic therapy, which often requires safety washout windows around SBRT, but for which prolonged treatment gaps are often undesirable for systemic control. In an attempt to expedite the time-consuming and lengthy overall treatment time, as well as the potential benefit for people with OMD to receive quick treatment a better optimized workflow is needed.
A proposed solution for expedited SBRT for OMD is the use of simulation-free radiation treatment planning, in which pre-existing diagnostic images are used to generate a radiation treatment pre-plan (as opposed to acquiring planning-specific image sets). This can be implemented using with online adaptive radiotherapy (ART) to refine and finalize the treatment plan at the time of first-fraction delivery, rather than using a standard simulation process. To account for inconsistencies between diagnostic CT and treatment sessions, automated treatment planning is critical for providing rapid online adaptive radiation therapy with full re-optimization based on the anatomy of the day. This can speed up the process of treatment delivery and optimize on-table dose computation. ART has been proven as clinically feasible and time-efficient in prospective clinical trials treating other anatomical sites. Similarly, simulation-free treatment is an emerging standard of care for urgent, palliative radiotherapy settings. However, to date, the feasibility of simulation-free SBRT using an online ART workflow for oligometastases has not been prospectively tested.
Therefore, the purpose of this study is to demonstrate the feasibility of a simulation-free workflow for oligometastases SBRT using online ART. 15 participants will be enrolled; 5 participants with treatment sites in the thorax, 5 with treatment sites in the abdomen/pelvis, and 5 with treatment sites in non-spine bone.
