Original Title: Radioterapia lattice en el tratamiento curativo o paliativo de tumores profundos, de gran volumen y enfermedad metastásica o irresecable

Authors' objectives: The primary objective of this report is to evaluate the effectiveness and safety of Lattice Radiotherapy compared to conventional treatments for large solid tumors, deep tumors, and metastatic or unresectable diseases. The specific objectives are: 1) To evaluate the effectiveness of LRT in terms of tumor control, symptom relief, survival, and quality of life; 2) To assess the safety of LRT in terms of toxicity; 3) To evaluate patient acceptability, satisfaction, and perspectives regarding LRT; and 4) To describe the most relevant economic and organizational considerations related to the implementation of this technique.

Authors' results and conclusions: From the bibliographic search, 8 articles met the predefined selection criteria. Of these, 7 were case series, and 1 was a cross-sectional study. Regarding the case series, they included a total of 144 patients with a mean age of 68.5 years. Six of the case series included large tumors (with a size cutoff between 5 and 7 cm). Three studies focused on a single tumor location (lung, breast and cervix). The doses at the vertices and periphery, as well as fractionation schemes, varied widely across studies. Regarding treatment safety, 169 adverse events were recorded, of which 65.8 % were grade 1, 28.9 % were grade 2, 2.6 % were grade 3, and 2.6 % were grade 4. Survival was measured from one month to two years after treatment. Among studies with a six-month follow-up, overall survival ranged from 50% to 86.4 %, while at 12 months or longer, it ranged from 46.7 % to 86.4 %. Median survival time ranged from 3.8 months to 16 months. The proportion of patients experiencing tumor reduction ranged from 80 % to 100 %. The percentage of tumor reduction varied widely between studies and across time points. Regarding tumor response, the partial response rate ranged from 13 % to 80 %, and the complete response rate varied between 17 % and 100 %. Four studies assessed symptomatology, all concluding that the intervention had a beneficial effect. Two studies analyzed quality of life, both suggesting that LRT may improve it, primarily due to symptom relief. The certainty of the evidence according to the GRADE system was rated as low to very low for all reported outcomes. Regarding the cross-sectional study, it was a survey involving professionals engaged in radiotherapy treatments. Most participants were from the United States. A total of 73 participants were included, 75 % of whom had not received specific training in spatially fractionated radiotherapy. About 45 % had used the LRT at least once, with the most commonly used techniques being intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT). Conclusion: Currently, the evidence on LRT for deep, large, metastatic, and/or unresectable tumors is limited and based on non-comparative studies, which precludes drawing definitive conclusions. More robust studies are needed to assess its effectiveness, safety and mediumto long-term feasibility. Safety • The safety of Lattice radiotherapy in deep, large, metastatic, and/or unresectable tumors is very uncertain, i.e., the available results are unreliable. In the published case series, adverse events were generally mild (grade 1 or 2), with respiratory events predominating in treatments for thoracic tumors. There are no results regarding the impact of tumor location and dose-response relationship on the occurrence of LRT-related toxicity. Effectiveness • The effectiveness of Lattice radiotherapy in deep, large, metastatic, and/or unresectable tumors is very uncertain, i.e., the results are unreliable. It has not been possible to draw firm conclusions on tumor volume reduction, tumor response or survival, nor on how pre-, concomitant and/or subsequent treatments may affect clinical outcomes. • The lack of studies directly comparing Lattice radiotherapy with conventional radiotherapy or other types of fractionated radiotherapy limits the comparative evaluation of its benefits and disadvantages. This lack of controlled studies, the variability between studies and methodological limitations do not allow definitive conclusions to be drawn. Implementation • The implementation of Lattice radiotherapy in clinical practice may require specific training of healthcare personnel in treatment planning and delivery. In addition, standardization of protocols is necessary to reduce variability in outcomes and ensure consistency in clinical application. Research needs • There is a need to develop quality clinical studies with controlled and tumor-specific designs that evaluate both the safety and effectiveness of Lattice radiotherapy in comparison with other treatments.

Authors' methods: We performed a systematic review of health literature until November 2024. We conducted a search in relevant health databases: • Specialized databases for systematic reviews and health technology assessment reports, such as Cochrane Library, Epistemonikos, and PROSPERO. • General databases, including Medline, Embase, and Web of Science. • Clinical trial registries, such as ClinicalTrials.gov and ICRTRP. Two independent investigators selected and reviewed the articles according to previously established selection criteria. The information was synthesized following the GRADE system and presented in evidence tables.

Project Status: Completed

Year Published: 2026

URL for published report: https://runa.sergas.gal/xmlui/bitstream/handle/20.500.11940/22601/Avalia-t_2453_Radioterapia_Lattice_NIPOENTRAMITE.pdf?sequence=5&isAllowed=y

Requestor: Ministry of Health

English language abstract: An English language summary is available

Publication Type: Full HTA

Country: Spain

Organisation Name: Scientific Advice Unit, avalia-t; The Galician Health Knowledge Agency (ACIS)

Contact Address: Conselleria de Sanidade, Xunta de Galicia, San Lazaro s/n 15781 Santiago de Compostela, Spain. Tel: 34 981 541831; Fax: 34 981 542854;

Contact Name: avalia_t.acis@sergas.es

Contact Email: avalia_t.acis@sergas.es

Copyright: Scientific Advice Unit, Avalia-t; The Galician Health Knowledge Agency (ACIS)