Objective Lattice radiotherapy (LRT) is a novel technique of delivering heterogeneous doses of radiation to voluminous tumors not amenable to surgery. Built from the conventional two-dimensional grid, LRT utilizes the power of new technology, three-dimensional radiation allowing the delivery of higher doses of radiation to small spheres, also called vertices, inside bulky tumors while limiting exposure to surrounding healthy tissue. The main goals of the study were the evaluation of tumor response and the overall safety of LRT in this cohort of patients with bulky non-small cell lung cancer. Materials and methods During a seven-year period, 10 patients with non-small cell lung cancer (NSCLC), who presented with bulky, unresectable tumors, were treated using a single fraction of LRT followed by conventionally fractionated radiation. Patients received one initial LRT fraction of 18 Gy in the vertices and 3 Gy in the periphery. After the LRT, all patients continued with conventional radiation: 25 to 29 daily fractions of 1.8 Gy to 2 Gy. Results With a median follow-up of six months (range: one to 71 months), the mean decrease in tumor volume was 42%. The overall survival of the entire group ranged from four to 86 months (mean 22, median 16). There was no mortality related to LRT. No significant acute or chronic toxicity was noted. Conclusion In this small cohort, LRT appears to be a safe and effective modality to treat bulky NSCLC. Further research is needed to establish its efficacy in the management of voluminous NSCLC.

The concept of spatially fractionated radiation therapy (SFRT) was conceived over 100 years ago, first in the form of GRID, which has been applied to clinical practice since its early inception and continued to the present even with markedly improved instrumentation in radiation therapy. LATTICE radiation therapy (LRT) was introduced in 2010 as a conceptual 3D extension of GRID therapy with several uniquely different features. Since 2014, when the first patient was treated, over 150 patients with bulky tumors worldwide have received LRT. Through a brief review of the basic principles and the analysis of the collective clinical experience, a set of technical recommendations and guidelines are proposed for the clinical implementation of LRT. It is to be recognized that the current clinical practice of SFRT (GRID or LRT) is still largely based on the heuristic principles. With advancements in basic biological research and the anticipated clinical trials to systemically assess the efficacy and risk, progressively robust optimizations of the technical parameters are essential for the broader application of SFRT in clinical practice.

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HighlightsIn a six-year follow-up the patient is alive and well with no evidence of disease.This case reports successful treatment of a patient with advanced NSCLC using LRT.LRT is frequently referred to as spatially fractionated GRID radiotherapy or SFGFT.Lattice Radiotherapy (LRT) is a technical extension of 2D Grid Technique.

The objective of this teaching case is to report the excellent results of using lattice radiation therapy (LTR) for the treatment of a large metastasis from ovarian carcinosarcoma. This new technical concept extrapolates the traditional spatially fractionated radiation therapy (GRID) technique to advanced three-dimensional (3D) high-dose radiation therapy using modern instrumentation in radiation oncology. We report a case of a 61-year-old female with a large metastatic mass from ovarian carcinosarcoma treated by this procedure with excellent clinical and image-based follow-up results for more than four years.