INRG

INRG stands for the International Neuroblastoma Risk Group, a global collaborative network of pediatric oncology centers. The group aims to standardize risk assessment, staging, and treatment planning for neuroblastoma, and to promote international data sharing and research. Its guidelines are designed to be applicable across diverse health systems to improve outcomes and enable meaningful comparisons of care.

History and purpose. The INRG initiative emerged in the early 2000s, culminating in the INRG staging system (INRGSS) introduced around 2009. A core feature is the use of image-defined risk factors (IDRFs) derived from preoperative imaging to influence surgical planning and stage assignment. The framework seeks to harmonize staging and risk classification worldwide, supporting consistent patient management and the design of multicenter clinical trials.

Staging and risk classification. INRGSS categorizes tumors using stages that include localized disease without IDRFs (L1), localized disease with IDRFs (L2), and metastatic disease (M), with infant-specific considerations such as Stage MS in certain younger patients. Risk grouping is based on a combination of INRG stage, patient age at diagnosis, tumor biology and histology (per Shimada classification), MYCN gene status, and other chromosomal or molecular markers such as 11q aberrations. This integrated approach informs treatment intensity and trial eligibility.

Genetics and biology. In addition to MYCN amplification, other genetic features—such as 11q abnormalities and DNA ploidy—are incorporated into risk assessment, reflecting their prognostic significance and helping to refine risk categories across populations.

Data resources and impact. The INRG Database (IDB) serves as a centralized repository of pretreatment and outcome data from participating centers, enabling large-scale analyses and ongoing refinements to risk definitions. Through standardized imaging, staging, and reporting, INRG supports international collaboration, research, and the development of globally applicable treatment strategies.