Stereotactic Ablative Fractionated Radiotherapy versus Radiosurgery for Oligometastatic Neoplasia to the Lung: A Randomized Phase II Trial

Single-fraction stereotactic ablative body radiation therapy for primary and metastasic lung tumor: A new paradigm?

Stereotactic ablative body radiotherapy (SABR) is an effective technique comparable to surgery in terms of local control and efficacy in early stages of non-small cell lung cancer (NSCLC) and pulmonary metastasis. Several fractionation schemes have proven to be safe and effective, including the single fraction (SF) scheme. SF is an option cost-effectiveness, more convenience and comfortable for the patient and flexible in terms of its management combined with systemic treatments. The outbreak of the severe acute respiratory syndrome coronavirus 2 pandemic has driven this not new but underutilized paradigm, recommending this option to minimize patients’ visits to hospital. SF SABR already has a long experience, strong evidence and sufficient maturity to reliably evaluate outcomes in peripheral primary NSCLC and there are promising outcomes in pulmonary metastases, making it a valid treatment option; although its use in central locations, synchronous and recurrencies tumors requires more prospective safety and efficacy studies. The SABR radiobiology study, together with the combination with systemic therapies, (targeted therapies and immunotherapy) is a direction of research in both advanced disease and early stages whose future includes SF.

Ten-Year Experience in Implementing Single-Fraction Lung SBRT for Medically Inoperable Early-Stage Lung Cancer

PURPOSE

To review 10 years of using single-fraction lung stereotactic body radiation therapy (SF-SBRT) for medically inoperable peripheral early-stage lung cancer.

METHODS AND MATERIALS

An institutional review board-approved prospective lung SBRT data registry was surveyed until the end of December 2019 for all patients receiving SF-SBRT with minimum 6-month follow-up. Doses used were either 34 Gy or 30 Gy. Outcomes of interest included rates of local failure and overall survival (OS), as well as treatment-related toxicity graded per Common Terminology Criteria for Adverse Events version 3.0.

RESULTS

A total of 229 patients met the study criteria. Patient characteristics included female sex (55%); median age, 74.6 years (range, 47-94); and median Karnofsky Performance Status 80 (range, 50-100). Tumor characteristics included median diameter, 1.6 cm (range, 0.7-4.1); median positron emission tomography standardized uptake value maximum 6.1 (range, 0.8-24.3); and 63.6% of patients biopsied. SF-SBRT dose was 34 Gy in 72.1% cases and 30 Gy in 27.9%, with patient and tumor characteristics balanced between cohorts. Overall median follow-up times for 30 Gy and 34 Gy were 36.7 and 17.2 months, respectively (P < .0001). At analysis, 55.9% patients were alive. Two (0.9%) patients developed grade 3 toxicities, and none had grade 4/5 toxicities. Grades 1 to 2 pneumonitis and chest wall toxicity were seen in 7% and 12.7% patients, respectively. Median overall survival was 44.1 months. Rates of 2-year local, nodal, and distant failure were 7.3%, 9.4%, and 12.2%, respectively. There were no significant differences in outcomes by dose.

CONCLUSIONS

This is the largest institutional series to date reporting on SF-SBRT outcomes for medically inoperable peripheral early-stage lung cancer and the first to report on a decade's experience in implementing this schedule. Outcomes from this analysis are comparable to published results from 2 randomized trials and validate the use of this schedule in routine practice. In the absence of phase 3 trials, this study should encourage increased use of SF-SBRT for inoperable tumors.

Identifying Candidate Biomarkers of Ionizing Radiation in Human Pulmonary Microvascular Lumens Using Microfluidics-A Pilot Study

The microvasculature system is critical for the delivery and removal of key nutrients and waste products and is significantly damaged by ionizing radiation. Single-cell capillaries and microvasculature structures are the primary cause of circulatory dysfunction, one that results in morbidities leading to progressive tissue and organ failure and premature death. Identifying tissue-specific biomarkers that are predictive of the extent of tissue and organ damage will aid in developing medical countermeasures for treating individuals exposed to ionizing radiation. In this pilot study, we developed and tested a 17 µL human-derived microvascular microfluidic lumen for identifying candidate biomarkers of ionizing radiation exposure. Through mass-spectrometry-based proteomics, we detected 35 proteins that may be candidate early biomarkers of ionizing radiation exposure. This pilot study demonstrates the feasibility of using humanized microfluidic and organ-on-a-chip systems for biomarker discovery studies. A more elaborate study of sufficient statistical power is needed to identify candidate biomarkers and test medical countermeasures of ionizing radiation.